[uhftx]

You could try and disconnect the 12V feed at the refridg. Operate it with a jumper pack or a separate 12 V source fused directly into the refridge terminals. This will eliminate your internal wiring which I suspect to be your issue. Chaffed wire or critter chewed and the wiring from the fuse panel to the fridge is shorted Plus and minus together popping your fuse.

You can run a separate 12V feed from your truck battery with long wires or just borrow a 12V battery or power supply. The current draw is only to power the electronics. The refridge when not on 120V is run on propane. The primary power draw in this mode is to actuate the gas selinoid valve and run the circuitry for control.