I used insulation material for a boat engine compartment. I't a layer of metallic reflective material, foillowed by a layer of high density foam, followed by a layer of rubberized lead, followed by another layer of foam and then the outer sheet of metallic foil. Used 3 M spary adhesive to put it on. Been about 10 years now. Purchased the material from Defender Industries.
2013 DS 4338
2015 F-150 toad with kayaks,bicycles and a Harley in the back