Our Coachmen Beyond is based on the Ford Transit chassis. Coachmen installs SuperSprings as part of their build. These are additional leaf springs and are designed to compensate for a constant added weight.
What we found was that on large bumps we had a pretty severe jolt. This was probably the leaf spring hitting the stock bump stop. [As a MN resident, I was surprised at some of the freeway potholes in some of the southern states. I thought those were exclusive to frigid climates.]
The company SuperSprings also has a product called SumoSpring. This is a spring encased in a polymer to provide a dampening effect. These replace the bump stops. Cost is about $300. The difference is that, when hitting a bump, their will be a gradual increase in support rather than an abrupt increase when hitting the rubber bump stop.
After a few emails back and forth, I settled on the blue lower density springs. These were recommended since we already had the SuperSprings and were looking more for dampening than support.
Installation was really simple. There are multiple short videos on this, so just search Youtube for Sumosprings. Access is a little more annoying with dual rear wheels, so I took them off rather than do everything from below. If you do decide to try this, have a variety of short socket extensions handy, as you need to be a little creative getting the socket wrench in and out. A second tip is to stuff a little foam or even paper towel into the socket so that the head of the bolt does not go too deep while you are trying to get the bolt started.
The instructions recommend leaving a gap of 1/2 to 1" between the Sumo and the axle stop. Since we already has SuperSprings for the added weight, the company recommended a small bit of pre-compression. We have about 1/4 to 1/2" pre-compression on the Sumos.
Here is a link to the company if interested. There are several useful videos from both the company and other customers on Youtube.
SuperSpringIntl
Review: OK, I will be the first to admit the possibility of a placebo effect, but both my wife and I feel that the general ride has been improved. There is a definite improvement when we hit large bumps, but we think it's smoother overall, probably due to the preloading of the new springs.
Photos of stock bump stop (orange) and the SumoSprings (blue)