It is entirely possible, maybe even likely, that the park pedestal is fine. A failed neutral within the RV would lead to the exact same condition. The frame of the RV would become hot and some of the current could shunt through someone touching the ladder if they were firmly grounded (which standing on very wet ground creates). If everything is working properly, there shouldn't be any current flowing to the chassis or the ground. The ground is a safety feature in the event a neutral fails. The search for the problem should be expanded well beyond the campground pedestal, especially if the campground employee correctly performed a few simple tests.