I expect you're about to make a major tuition payment in the "University of Life."
Let's start with a few observations that ought to be vommon knowledge by now:
1) These days, GFCI's generally trip because there's a problem;
2) RV parks more than a few seasons old are wildly overloaded and badly degraded; and,
3) The RV's themselves are invariably a vipers' nest of worn, damaged, and improper wiring.
Need I go into detail?
What I suggest you do is that you hook up a nice big electric heater (or, better yet, a 'wall shaker' air conditioner) to each circuit to demonstrate that the problem is NOT with the breaker.
Next explain, using small words and short sentences, that it's likely there is something in each RV that is trying very hard to kill someone.
