Many RV's pop GFCI's Prime suspects are water heater. Fridge and converter.
TURN OFF all breakrs and plug a drop lamp into the outlet along with the RV via adapters. Put the light where you can see it from the breaker panel in the RV.
now starting with the main breaker turn on one at a time wait a few seconds then the next and the next till the drop lamp goes dark (Tripped GFCI. turn that one back off. reset GFCI and continue till all breakers that do not trip GFCI are on.
Now figure out what's on that breaker.