Just make sure the exterior of the trailer is scuffed, dirty etc. Signs imply equipment which might be valuable.Brother and I had long discussions about building something similar. Most animated exchanges centered on exterior signage that would disinterest the majority of casually curious folks.
We settled on "Waste Water Remediation Service" or "Sewer Survey Service" , followed by "Bio-Hazard Testing Services"...
I think the original idea was for stealth camping where it wasn't allowed. Looks like a trailer not a camper.What's the goal? a trailer that can be lived in, that looks like an equipment trailer?
It's every bit as insecure as a travel trailer. I am not sure it's going to deter a thief. It will be as much a "target of opportunity" as any travel trailer.
My friend did something similar to a horse trailer. Cost him a small fortune to get it right.