Bivouac Jack--

I've been doing exactly this sleeping in pants thing for about 6 years, since I made myself a pair of primaloft pants for winter use. The idea was a light weight outfit that would dissipate moisture on an extended winter trek with just body heat. It's all synthetic (Primaloft, polarquard) because down doesn't breath all that well, so to dry clothes with a down bag the vapor barrier is a bag with you and your damp things inside; with synthetics you wear a vapor barrier suit next to skin or almost, then your damp things with a stretch layer over, finally the fiber-insulated outer layers. I do use a 2 lb synthetic bag over, with a home sewn windsack sleeping bag cover to keep snow off. Also, I have an insulated Primaloft Parka. An elastic draw cord helps the midriff heat leak. Walt