Stereo receiver to avoid voltage drop

There's no way that a compressor fridge will use less power than a fridge running on propane. On the ferry, you just shut it off the propane for the time that you're on the ferry and don't open the fridge door. The ferry trip time isn't an obstacle unless you're taking the ferry to Alaska. I've turned mine off on the trip to Vancouver Island and that's probably the longest ferry trip around here. Turning up the temp on your fridge probably won't make a noticeable difference in your 12V power consumption. I really think a propane fridge would solve all of your power problems, at least until your furnace uses up all the propane. I guess I don't understand the concern about running a propane fridge on back roads. I suppose if you had a 3-way fridge you could run it on 12V while underway without having a propane concern or a power consumption concern.