Bill, I assume there is no sleeping bag in this scenario. My setup is a military poncho for the roof/shelter.The grommets make this the easiest to tie down. I carry a huge orange bag supplied by Barry @ Blueline. It is a thick, awkward affair, but I like the durability and can almost cocoon my 6'2" frame inside. This is my groundcloth. I now have the wind and rain excluded ( more or less). I am still running on my internal furnace, so a fire and any emergency rations are neccessary. My poncho liner and clothing are going to be my insulation ( excluding natural materials in your son's case). Space blankets are also available in sleeping bag configurations. They cost more, but trying to secure a space blanket in weather is a nightmare ( and forget refolding them). Clothing is going to be the crucial element. I always carry a watch cap and mittens. Even spare socks can go over cold hands. I've made several such impromptu shelters. By morning I was snoring so loud the bears were giving my nest a wide berth.