I have the same pack and I as well am going to add a frame to it. I just about have all of my bob items but the pack is starting to get a little heavy. I was going to use my large alice but I love all the pockets and storage areas this bag offers. My plan is to add an external alice frame and use the little shelf along with it. I plan to get heavy material and get a tailor to attach it to the top of the pack and heavy webbing for the bottom kind of how and alice frame attaches to the alice pack. the waist belt will slide out it is just velcro holding it in its pocket. As for the shoulder straps I plan to cut them at a length so I can use them again without the alice frame with a 3 bar slide.
aye the 3day panels will fit in some of the clones did it on friends Tru Spec one. I've used cutting board material and lexan in some packs I've never bothered adding metal stays but guess it'd be easy enough Packs that top load(traditional ruck styles) I'll use my sleeping pad as a tube then pack in it, keeps the pokes down.