I didn't read through the rest of the thread so apologize if this has already been mentioned, but haven't seen the OP mention this.
I had a GFCI outlet in my house that would always trip. Turned of the house electricity and took a look at the circuit to see if it was wired incorrectly. Was wired right. Replaced it with a new GFCI outlet and have not had it trip since. Previous outlet must have went bad or was bad from new, this was an existing house we bought.
Most RV ac 120v outlets are just house supplies. Maybe just switch it out and see if your problem is resolved.
