two fires and sleep between them..if you have the wood make the reflector big.i have seen photos from the 1900's and these guys had the logs shoulder high in front of a lean to.if you have no way to make a fire i would say a snow shelter packed with leaves or dry rush,grass would be your only hope..and don't count on sleeping much in that sort of sitution. the best book i have read on winter camping is "paradise below zero" by Calvin Rutstrum. because the book is somewhat old you will not find anything about space blankets or gor-tex.just how they did it in the old days.