I would like to have a warmer TC floor... any ideas?

I have a 04 Silverado with Linex spray bed liner with a rubber mat sense the truck and camper were new, absolutely no rust. The 1161 rarely comes off the truck and has been garaged when not in use which is not often. As far as insulation with this set up not sure because have always used it this way. When we winter travel I usually put the carpet in, have stayed warm in 0* weather.