Revisiting this, I wanted to show my version of the 50 amp device Lee linked to earlier in this thread. Simpler versions might suffice, but this one seemed to cover all the bases. The documentation on the linked page seemed to be a bit dated, and not all the parts were as available as it implied, so some improvisation was necessary. The digital voltmeter was a cheaper and more accurate upgrade, it seemed to me. A simple 30 amp adapter plus 3-outlet expander, as shown on the link, just uses the digital voltmeter and one circuit analyzer off the 50-amp concoction, and both devices store easily in a small Rubbermaid box in my power cord bay, handy to use prior to plugging in anywhere.
Our on-board Surge Guard has protected the coach systems several times that I know of, so these devices may be unnecessary given the odds so far experienced. But I couldn't resist the temptation to put them together anyway. Besides, they may perhaps present a park manager with indications of what may be behind any issue we do run across... again. I do need to proclaim I've yet to actually try the 50 amp unit, and likely will not be able to for awhile due to travel limitations for the time-being. But having followed the instructions, in principle it should do the job.
Sorry, as is common here the pix don't always translate right-side up.
Joel