Yes, definitely overloaded and pulling a trailer over 2 days of wash board roads. The trip is 3 days and so I not sure how much they will like slowing down and making it take longer.
Oh well, that's what's doing it - bump stops are NOT stopping the dampers from bottoming out.
One cure is deeper bump stops or inch spacers under the bump stops, but all these "cures" merely throw the excess forces somewhere else, and in this case it will be the chassis which takes the brunt of it, and which may fail.
Never mind, welding a broken chassis isn't such a big job - once you get the body off.
CharlesY