I'm setting up a truck cap for camping, one to two night stays. Built a cot frame just above the wheel well. Layed one inch foam board on the floor and will cover that with one half inch plywood to protect the foam. Cut to fit two inch foam board around the truck bed sides (has bedliner with a fiberglass cap). Made a small stand to hold a one burner propane camp stove and also surface for tent heater. YES, I will have the two side windows open about one and one half inches and heat turned off at sleepy time.. Storage under cot frame for anything. Storage under the cooking stand also. Everything comes out of the truck bed and fits in a small corner in the basement. Looking for foam pad for the cot, checking yard sales and furniture stores. Built on the cheap side, used odds and ends left over lumber from coffin making. Glue, screws and foam board has been the only expense. I have tent camped for about thirty years and this will be interesting and cramped!! When totally completed I'll post a photo.