I made my own panels. The panel conversions are like $1K. I bought a bunch of sheets of Corroplast. Then I sprayed foam on them, swirled for about 40% coverage and laid a piece of foil/foam/foil insulation on that. Let it dry to bond and then installed. For installation, I used self tap screws to screw sections of plywood, about 4' x 6" strips, to the cross members. Used poly washers and torx head screws to attach those panels to the wood. Then, a strip of marine tape on the joints with aerosol spray plastic over that. It's a pretty solid set-up. I made sure to have a few vent holes in the front and the rear along to exhaust the heater ducted into the underbelly. Took all the kinks and excess out of that too. Now, if I have a problem it is just remove one panel and I can screw it back up. I spent about $300 on coroplast, insulation, foam and wire ties.
The big motivator was I had a short on the main power cable. They had pulled it, or yanked it, against a metal bracket and cut through the PVC wrap and the individual hot leg insulation. That is now all protected in foam, or when it passes through a member, the member is wrapped with foam. Took me about 3 days tinkering around to get it all done. but well worth it.
The inside, the MDF board for the accent lights above the couches and dinette came loose, just crappy workmanship. I tried to fix one, next trip, loose again. I tore it all down, put in foam board, dimmable LEDs lights and the shiplap. Here is what that looked like about half done putting up the shiplap, and finished. Wife loves it and it looks so much better. I guess it comes from being a racer and an engineer. I hate crappy work and I'm not scared to tear stuff apart. I rebuilt the engine in my Super Stock car in the back of a trailer while one of my crew was driving to the next race on I-70 doing 70 mph.
