Wow, glad I caught the thread. You have a lot of work ahead of you Marty.
After rebuilding my trailer, the next RV I have is either going to be built by me or will be aluminum and fiberglass. These stick construction RVs are a joke. My trailer has the same construction as your camper.... small lumber, particle board and staples. The sheetmetal used acts as most of the shear in the walls. Stupid design.
Just take all the trim and windows out to re-seal them. Use the butyl putty under them and the silicone over that. It'll help stop leaks. The lights are a PITA and that is where a lot of my leaks came from.
My trailer still has a leak in the back bathroom area and one of the side windows. I've chased them down again and again and just can't find them. Too many places to possibly leak.
Take your time and seal it up best you can, it'll last another 10 years. I started covering mine in the winter, it helps a TON.