You sound like you're in really good physical shape, and that helps a lot as long as you don't try to push it. If you do, you'll lose all the previous time gained trying to recover the second day or going slower because of it.
I wouldn't say awesome, but better than most 47 year olds.
Egads, the Potomac. Comparable to swimming in a disease-infected sewer. You've got your tetanus shot up to date, right?

There *are* lots of bridges there, but in any sort of homegrown cell terrorist attack, all of the ones leading in/out of DC would probably all be blown by the bad guys to keep the panic inside DC as high as possible, or closed by DC police to keep the WH as safe as possible.
Blowing up a bridge so that it is impassable by foot is a little harder than it sounds.
Your answer begs the question: do you know how to hotwire a boat? (Something to learn asap if you don't.) Either way, just-in-case, I'd look into getting a dry bag for your gear and clothes. You can fold it up and tie it to the outside of your "RLH" bag with some shock cord or bankline. Even if you find a rowboat, or end up caching an inflatable one (they're really inexpensive these days) it'll help keep stuff dry.
Keep in mind that if you're E&E, boat motors are really loud and attract attention.
Hotwiring a boat is easier than a car. Less anti theft mechanisms built in. But yes, stealing a canoe or rowboat would be far easier. And I already have a drysack inside my backpack (GHB). Never heard of bankline - will look into it
With a dry bag full of air to help you stay afloat, you could probably launch off at Georgetown Waterfront Park and kick out real good, the current would take you right over to Teddy island, and then you could walk across it and take the foot bridge the rest of the way over into VA. (If you're in DC a lot, I'd really recommend looking into burying a small essentials-only cache on the island.)
Thinking along those lines, snagging a life preserver would probably be pretty simple and that would get me across the water far more easily. And burying a cache on Teddy island is a great idea.
The good thing about that area is that the weather doesn't get *too* cold and very little snow, so your emergency blanket and basic lighters will do the job IF they don't get wet or too cold (I know it does get icy there). Wrapping your lighters in zip-locs to keep them dry would be a good idea. Keeping one in your pants pocket or shirt pocket would be good, too (to keep it warm). With those plus your knowledge on basic debris shelters (or using debris to stuff your clothes) you can stay toasty. Slip a business-card size fresnel lens into your wallet for backup fire starting any time there's sunlight.
I like the idea of a pocket fresnel lens. I've already vacuum sealed the lighters.
Your real environmental danger is going to be the heat index in the summer and staying cool and hydrated.
I'm in Hampton Roads. It's been a couple decades since I hung out in the Falls Church area on a regular basis. I don't remember if that area gets the humidity that we do, but our heat index can be lethal. Whatever you do when you're paring down or rearranging your bag, don't get rid of that silcock key. You'll be going through water like a sieve and with the area you're going through, it'll be a lifesaver. I'd recommend that you find a place to put some gatorade or powerade powder packets. You're going to need those electrolytes, because you'll be sweating liters of water.
I have a Sawyer mini in my GHB. If I ditch the Datrex, I'll have room for it. I'll just move the Datre to the GHB. And adding electrolyte tabs.
Ditch the Datrex bars. They're very heavy and take up a lot of space in that little pack, and you won't need them for a 2-3 day walk. (Remember you can go three weeks without food.) Replace with jerky for lightweight protein and some hard candy or dried fruit for sugar if you feel you'll *really* need food, and the gatorade/powerade packets. Personally I'd forget the idea of food all together and maybe carry a pack of gum for when I get hungry - it's an urban area and you've got a P51, finding a can of food even after extensive rioting isn't going to be difficult.
I'd also ditch the Chlor-Floc tablets and replace with a mini Sawyer water filter. With it, you won't need the tabs, can drink straight from a water source with no waiting, and can use it and its included tube to filter water straight into your collapsible bag.
Unless you're planning on using it to look around corners, ditch the signaling mirror. This is a run like hell bag, not a "hey Mr. Plane, look, I'm down here" bag.

Even if you are planning on looking around corners with it, a dentist's mirror will work much better in an urban environment and will keep you from attracting attention and getting your hand shot off.
Yeah, I haven't added the signal mirror yet. Wasn't entirely sure of its benefit in my likely E&E scenario. Good thoughts.
Why the snare wire? You don't need to try to catch rabbits and squirrels on a 3-day walk through a mostly urban area. If it's to set up a warning perimeter with cans while you're sleeping, fishing line will work just as well, take up less space (can be wrapped around something else without getting kinked), and weigh less.
I was planning on the wire for traps or alarms. I already have it. Maybe I'll get some fishing line and wrap it around the other lighter.
I'd lose the hacksaw blade and replace with heavy-duty wire cutters. If you need to cut branches for fire, you can do that with your Cold Steel folder and careful batoning. Sawing through a lock or a wire fence is going to take too long and be too noisy. You've got your lockpicks to get through a lock, get wire cutters to get through a fence.
Love the idea about buying a pair of fence cutters. If I ditch the Datrex, I'll have room. But keeeping the hacksaw. Can't get through a padlock with fence cutters. Not 100% proficient with lockpicks yet.
Put in an extra pair of socks. Seriously. (Use the space the datrex bars used to take up for that.) No matter whether it's hot or cold, your feet will be sweating and you'll need to change into a dry pair of socks to keep from getting blisters and foot rot.
I really don't think you'll need the pen and pad. With frequent review of maps of the area and your compass, you should be good. (Plus you're going to be passing convenience stores on nearly every corner that have local area maps.) It's not like you're going 500 miles. If you really feel you'll need to write something down, get a fine-line waterproof sharpie instead of that pen and use your forearms to write on.
Again, good thoughts. I think you could drop me within 30 miles of my house and I could figure out how to get home. Have a sharpie in the GHB.
Lose the paracord. You don't have a tarp to string up and you're not going to be rapelling. If you want cordage, replace the paracord with an equal length of #36 tarred bankline. Lighter and less space.
Again, looking into bankline.
Why the cash/coins? You've already got this in your wallet/pants pocket. If you've had your wallet taken off of you, you're not going to have your RLH bag, either.
Cash is king. Not gonna talke me out of this one. I probably have about 500.00 on me at any given time. It's served me well to get me out of lesser situations.
Trade both the wet wipes and the alcohol wipes for Benzalkonium BZK First Aid Wipes. Dual-purpose, antiseptic, and in the case of a bio/chem attack, will kill stuff on you that alcohol and wet wipes won't.
Good idea. I'll swap out from my med kit. Pretty sure I have them around here somewhere.
I'd find a way to add a monocular. One with night vision if you can afford it (they run $150-$200 these days.) Being able to see threats ahead of you in an urban area is going to save your life. (Like looking at the dark areas under an overpass.)
I have a cheap Tasco that is OK. Not in a kit. A thermal monoc would be nice - will put on the wish list.
In the summer, switch out your watch hat for a boonie hat. You'll need the shade, and it folds up just as well.
I always have a ball cap in the car somewhere.
Okay, truth time. You're within 50 miles of DC, Ghost.
You NEED potassium iodide tablets to protect from radiation, because DC is target #1 no matter what the scenario. You NEED a few good filtration masks for chem/bio attacks. (3M 8000 Particle Respirator N95 are inexpensive on amazon.) The tablets take up almost no space (especially in the bubble pack form), and if you can fit one mask, you can fit five because they nest inside of each other. I'd also recommend getting a little keychain Rad meter to hang off of your pack or keys.
I've got a neoprene mask with particulate filter and N95 I used in Afghanistan. Probably a good idea to add it into the RLH bag. And you are right about the PotIo tabs. Adding. The keychain rad meters are pricey, but I think you are mosst likely correct that it is worth adding.
Hope this helps. Best of luck to you. I sure wouldn't want to be that close to DC, heck I hate being *this* close to DC and Norfolk. Have you considered moving?