I have a coleman sleeping bag that has come to the woods with me before. Its all soft material inside and out, so no noise. You can certainly hack it up for foot holes and stuff. I you know someone that can sew a little, put some elastic around the openings to seal you inside. Seems reasonable to me. I agree, 300 for the heater suit is a little on the hefty side. IF you are doing it, you may want to get a McCheapo brand one, just a real cheapy, and chop that one up first for a prototype. Let us know how it goes Don!