Tinner. You mention tripping the GFI on electric. You have a grounding issue. You don't have a good ground somewhere or you have electricity leaking to ground somewhere in the camper. If you had an overload on the circuit the breaker in the main panel in your house would trip. I suggest you turn off all the breakers in the power panel in the trailer and wait 3 to 5 minutes to see if the GFI trips. if it does trip you may have a problem with the Inverter. you then need to disconnect the 12volt leads coming out of the inverter and see if the GFI trips. If it doesn't trip your inverter is good. Connect up the 12 volt leads to the inverter. Then turn one one breaker at a time and wait 3 minutes between breakers to see if the GFI trips. If the GFI trips when you turn on a breaker you have a problem with that circuit.