early game shelter could be made of a rope and two twigs and you simple tie down a tree as cover. You'll loose the materials the following morning. It's what you would normally do if you are to survive in a forrest, still not a vialbe option for the late/midgame, for those i have no idea, maybe a couple off boards tied together to form some sort of roof. Should no be very big, basicly only to allow the player or maybe the crockpot to be there