I removed the vinyl covered panel at the front of the overhead mattress on my C to check for water leaks/intrusion. There is fiberglass insulation at the very top where the front cap meets the roofline, and there were two pieces of fiberglass insulation at the bottom of the cap, laying on what I guess would be the "floor" of the cap. these are about 2 1/2" thick, and don't really cover that area. There is no insulation in the 20 or so inches between these two small pieces, and the insulation at the top where the cap meets the roof. I'm thinking about insulating the cap to help keep out the cold/heat. I was thinking about using soft foam such as used in upholstery padding, or older foam mattresses. Not memory foam, but something lighter than that. Is there any reason not to use the foam? I don't know about sweating, would that be an issue? I figure if I ever did get a leak, the fiberglass insulation would just get soaked and have to be replaced. The foam could be removed, cleaned and put back in. Anybody have any suggestions or advice?