I'm also short on how that RV works so a thought that you may want to consider and look at how much trouble to do?
I took a look at the drawing and did a snip of what i think you have. Understand that you are tripping one of the 20 amp breakers at the load center as I've marked?
Click the snip for a better view but the Full drawing of the 110AC is here:
One way to begin to cut the chase is if you have reasonably easy access to the two breakers, would it be practical to swap the wire from no. 1 and no. 2 on the breakers?
If the same breaker still trips, that would indicate a breaker problem and then I would go for changing it, but if the tripping follows the wire to the different breaker, I would look for trouble on toward the AC unit?