I use a short pad made from a foam called Low-E insulation. It's a polyethylene foam with an aluminum coating on each side and It's under 1/4" thick. I've got a pole barn that's insulated with this stuff and had some left over pieces. I cut a 26" X 48" piece and made a fanfold pad with duct tape hinges. When folded, it provides padding in my pack. I use it under my inflating pad. I use a Z-Seat pad under my feet. The Aluminized Z-Rest pad may work, but I don't have one and can't say. I have a cheap Chinese EVA pad that is Aluminized on one side, but I've only used it to make cozies. I've used this setup down to freezing with my quilt and been quite warm. I'm not certain how sleeping pad R-value is measured and I wonder if it is reduced by compression, just like the bottoms of sleeping bags. A reflective layer might be better in this case.