A sample wall section that I saw for a Renegade motorhome/toterhome had an aluminum frome inside the FRP. I believe the tubing was 2 inch. Polystyrene beadboard insulation is between the studs and I believe the inside is luan plywood. I don't think they use the studs in the race trailers.

Does anyone know of another manufacturer besides Renegade who uses FRP? An aluminum skin with metal studs would not be the most desirable in a cold climate.

The one thing for cold weather use that the truck conversion manufacturers are weak in designing is enclosed holding tanks with insulation and heating. I even had one rep who was displaying a motorhome with open holding tanks ask why would you need to enclose them. I explained that the build up of ice under the chassis would coat the tanks and the dump valves. He said we can put pad heaters on the bottom of the tanks. When I asked about insulation and how would you dump the tanks in the winter if there was ice buildup and he just gave me a blank stare. He did not understand what I was talking about.

That is one drawback I have seen with the truck conversion mfr's. They come from building rigs for the racing market and auto racing is a warm or moderate weather sport.