on my first ever winter camp out years ago over night my boots froze solid. I couldn't get them on and the lases stuck straight into the air. Since then when it has been cold i have dried and cleaned my boots as much as possible and they have joined me in my sleeping bag. They stayed below my feet (i was small then) it seems to me though that in a hammock my boots would slide down to the lowest point under my buttocks and be problematic. What do people do with their boots to keep them warm while winter camping?