Hard to say from your description. Have you done any testing to see if you might have damaged the circuit breaker? The GFI breakers can be somewhat sensitive sometimes. I'd try plugging the trailer in to a different breaker, using a different extension cord. You also need to be sure if you're tripping from a GFI fault, or circuit overload. I'd also see if the refrigerator would run off gas and battery, which will help pin it down to the AC heating circuit which is the most probable if the fridge actually is the problem. You should have DC fuses in the control board circuits that would be blowing if there is an issue there.
