What's outlast? Sounds expensive lol! I'm starting to plan my undersuit too so I'm looking for ideas too
It's a material originally developed for NASA. something about little capsules in the fabric...might get more information with google... I found this.. http://www.outlast.com/index.php?id=1&L=0 It may be expensive though, I think.
I just happened to mention the under suit to a friend and she came up with the idea and bought the material. She says shes going to make me a suit from it.