Hi, My wife and I just bought a 1988 Terry Resort 24' fifth wheel and we're in the planning process of renovating it. One of our first projects is to upgrade the insulation. I haven't had the chanc...
What about adding furring strips to the inside to make the walls thicker and adding a layer of polystyrene foam. Or remove the siding, (easy job, just start at the top and work down. And add a layer of 1/4" to3/8" thick foam insulation board like they use under residential vinyl and metal siding. It won't offer a lot but it will seal up all the gaps. Just sayin...