I bought a beater, tore it all down, and installed insulation for two weeks. It was a 6 mo. project.
An alternative could be to buy a cargo trailer and insulate the heck out of it. Install a bed, a porta-potti,a heater, and carry water in jugs. Showering would have to be done off-site like in a fitness club, YMCA, truck stop or what have you. The simpler you can keep it, the better off you'll be. If you're parking for more than a few weeks at one spot, skirting is a must-have. 
Like Peg Leg said, make it a cooler.