I've traveled with the fridge on propane many times over the past 25 years without a problem. That's not to say a fire can't start there. My current Dometic fridge had a recall performed a few years ago when a metal shield was installed around the burner area, including a thermistor to detect heat from a fire. That makes me feel safer but the thought remains that there's still a flame back there. If the trip is fairly short I leave the fridge turned off since it will retain its coldness quite a while if not opened.