Jeff-
Been there, done that. When you turn it on to propane, can you hear it fire and burn for 15-30 seconds before shutting off and giving you the "no FL" message? If so, you have a problem with the flame sensor, which is not sensing or not communicating that there is a flame. If not, you have a problem with either the fuel supply or the ignition.
My problems have been with the flame sensor, so I'll offer some thoughts on that. I had that problem a couple times. A mobile RV repair man came out and replaced the flame sensor, it would work for a little while (like no more than a day or two), then fail. He replaced the sensor again at no cost, but same result. Last year, I was tinkering around with it myself and undid the electrical connections to the sensor and cleaned them off real good with some emory paper. Put everything back together and it has now worked fine for a whole season (of admittedly light use). Another thing to try is to check and make sure the sensor is close enough to the flame. That may require a slight bending of the mounting bracket, if my memory serves.
Those are just a few ideas. Others will probably have more expertise. It's not too hard to get access to the flame sensor by taking off the outside plastic vent. There should then be a box-like cover over the flame outlet and sensor.
Edit: Has the fridge been running on propane for the first part of the trip? I assume you've been successfully using the furnace and the stove. If not, you could have a problem with air in the gas line. Best way to purge that is to run the stove for a while.