Is the exterior fiberglass or aluminum? Can you post some photos of the areas you're concerned with?
When I re-did the interior of an RV years ago, I just went to the local home store / lumber yard and used the same wallpaper, wainscot, paint, carpet, etc that you'd use at home. It may not be applied exactly the same, but the materials are the same.
There's a vintage thread / group on IRV2. Do some searching (or ask some questions) over there. I'll guaranty, someone there has done just about anything you can imagine to an RV.
Good luck with the project, and keep us up to date on your progress (photo illustrated is always enjoyed).