What about using your Mercedes diesel as a "generator?" Essentially using an inverter hooked up to the battery, and the engine to keep the battery from draining down. I thought about that a while ago as an economical solution to the periodic short-lived power outages here, where my main concern is keeping the refrigerator cold and tropical pets warm, and maybe powering the computer for entertainment
I'd just run a long extension cord inside. I would imagine that the Benz wouldn't use much fuel at fast idle, and I have a small supply of biodiesel around.