Seriously though, there are always truck campers up at the ski hill. How do they do it? Well, it's not magic, but many of them have really upgraded their rigs with extra insulation, windows, batteries, heated valves and ducted tanks, outside showers insulated, under bed insulated with air ducts, vents and just good stuff. We camped down to 8F and just got slushy water in the morning after a bit of work on my part to get it going. Man, that bed was so cold.
But, you won't be able to do it with your short box 3/4 ton. Nope, just impossible for what you want it to do.
