Insulated mine w/some heavy duty stuff CW Techs used to use. They no longer carry it, but I think J.C. Whitney does. It's about an inch thick of heavy denisty flexible foam w/a piece of vinyl sandwiched in the foam. It also has a foil on 1 side. It's kind of pricey but, it really does the job. Just found it under insulation sound/heat in JCW current cat. Comes in 1/2" & 1". 6sq' or 12sq'
Hinckley, Ohio, 00' winnebago Adventurer 35U,
07' Saturn Vue, SMI Stay-n-Play, Blue Ox Aladdin