I would suggest you paint on the pick up truck bed liner material. It can be done in white to help keep the coach cool, it sticks like mad, will insulate because it will be 1/16 or 1/8 inch thick. Tough as anything, can be dyed to any color if you don't like white, and is not slippery if you ever have to walk on it.
You could have it professionally sprayed or brush it yourself.
It is not necessary to simply repeat the mistakes of the past. Anytime I do a project I always try to make the end result better than it was before, much more satisfying that way.