What could I use?

[WRMZ71]

Next weekend I'm putting new rocker panels in my truck and patching up a couple of holes that were drilled in the floor(for what reason i don't know) When I"m done with the floor I want to put some sound deadener and then carpet over the top of that to insulate my cab real well during the winter. I was thinking I should probably put something over the metal like that por-15 stuff or whatever its called. The cab is stilll on the truck so I can't go nuts doing all kinds of stuff to the cab. I just want to keep a little more heat in there during the winter. Does anybody have any good ideas on what i could use or should I just leave the metal and then put the sound deadener on from there?