An underlayer of CoolMAX fabric might also work as well. It's what they use as an underlayer in athletic armor & padding to wick away sweat, almost like a cool version of synthetic fleece. Sew it into the inside of your undersuit.
nice, i like your ideas. I was thinking about a cooling vest but this might actually work all over and keep "other areas" cool as well. Keep the thoughts coming, I really love it when i get peoples opinions.