I store my 'C' in a building that I own that has a 30A power receptacle and its own gas furnaces. the 'C' is plugged in all the time. When not on the road, I turn the fridge off and prop the door open. I turn it on a couple days before I head out. I also have an upright freezer in the building for easy transfer before pulling out.
Here's a tip: Before I take off on a road trip, my upright freezers at home and the building get a plastic glass of water placed on the shelf a few days before departure. The day I leave, I put a quarter on top of each frozen cup. If that quarter is on the bottom of the cup when I return, everything in that freezer thawed and re-froze while I was gone.