Just a thought to be tossed around:
If you are just trying to keep a fridge operating on propane for a short time, a small 12V or 2 6V gel cell battery connected to the fridge control board will do it. Unplug the 12V connectors on the fridge control board, plug in your battery and secure it in the fridge compartment. Secure it on the left side away from the burner of course. Disconnect yours and reconnect the original connction when you get to shore power and recharge yours.
Depending on the size of the battery it will keep the fridge operating on propane for many hours. It will need to be recharged after a day or so, depending on the Ah of the battery.