What type of material are you guys using as insulation? The aircraft insulation sounds interesting, and I saw that one guy is planning on using surplus sleeping pads. I'd be looking for something that's going to be a good thermal barrier, but sound-deadening is also something that I imagine might be equally important to a lot of us. The other thing is, I don't want to give up the ability to hose-out my cab. I'm going to put a lot of work into making Mah Deuce more comfortable to drive, but I don't want to make it much less rugged. That means no carpet, and no water-sensitive insulation.
I've been really pleased with a paint-on sound deadening product called Second Skin that I've used in the cabs of several of my trucks, and I painted the floor of my M109 box with it before I put down a layer of 3/4" plywood (had some left over and figured it couldn't hurt). It's pretty durable and does reduce the noise inside a truck cab considerably, but it isn't going to do much of anything to regulate temperature.