I'm the kook here that regularly uses mylar foil bubble wrap to sleep on. I'm just so cheap I guess. My 24" x 74" piece weighs 10 oz. It isn't much padding, but the mylar foil really reflects the heat. My wal-mart blue foam just had no compressability and was hard as a rock. I would buy something else thin and light, if it would just compress a little. The best use of mylar foil is a small meal cozy/ fire fan/sitting pad/foil hat.
Live to tell.