One of the downsides of having a rear bathroom is that the dump fitting is in the rear corner of the trailer, which exposes it to potential bottom-out damage when pulling onto or off of a sloped surface.  The problem is serious enough that I would pull out of our driveway without the weight distribution bars on, as the rear axle sag on the SUV would raise the back end of the RV up enough to avoid bottoming out if I was careful.

The designers of the RV installed V-shaped skid points so that the plumbing would be protected from bottoming out:

By the end of last summer’s vacation, we had bottomed out enough times that these members had been bent to the point of being useless.  I welded reinforcing stock on as well as castors:

When I took the trailer out for inspection, the casters worked very well.  Let’s hope they hold up!