Solar is more of a "why not?" type of thing than "why?". At the minimum, 100-150 watts of solar and a multi-stage charge controller ensures that the batteries are topped off when the rig is in storage.
Add some more, you can replace the absorption fridge with a compressor fridge.
Add a bit more, and the amp draw from the furnace fan is taken care of. Add a bit more, and augment the battery bank, and you can use the microwave and other appliances.
The beauty of solar is that once the system is set up and wired, it is passive. Just watch the electricity flow in.