We currently have one rack that is approved for use on RVs and Class B vehicles, and it's the Superclamp HD. We are looking to expand that selection in the future, but for the time being this is the only option. None of our racks are approved for use on any kind of trailer or towed vehicle.
There are a number of variables that adversely affect a bike rack that's used on an RV; the biggest one being movement, or motion. Much of this is a result of how said motion is translated to the body of the vehicle and anything attached to it, like a hitch or bumper, etc. The suspension characteristics and resulting leverage applied to external apparatuses is completely different when compared to a conventional car, truck, van, or SUV. This can and usually does fatigue components in a way that can lead to catastrophic failure.
The Superclamp HD has been reinforced and designed with this kind of variability in mind, and is mechanically over-engineered to withstand such force.