Originally Posted by Elkman
It is incorrect to state that the Sprinter chassis is designed for commercial use and equate its use as a commercial van operating at 70% or less of its GVWR and its use to support a motorhome that puts it at 100% of its GVWR most of the time. There is not much in the way of reserve capacity for the chassis or the suspension or steering components.
When I evaluate a course of action and the risks involved I ask myself what is the worst that can happen and can I and my passengers deal with it. I don't hope for the best and go for it regardless.
You've hit upon a subtle thing regarding many of the later model Class C motorhomes available -> they are pushing the design limits of the chassis they're built on so much that there isn't much left in the margins for their braking, drive line, suspension, and frame systems.
This is probably going to continue unless Ford and/or Chevy continue offering a Class 4 chassis series chassis going forward. The current MB, new Ford, new Ram, etc. delivery van type chassis don't seem to be available above about the one-ton Class 3 chassis series.
What is still needed going forward for a bit more rugged small Class C use is a chassis that falls in the sweet spot between the 3 series and the 5 series of chassis. Both the Ford E450 and Chevy 4500 cutaway chassis fill this need - but how much longer are they going to be available in cutaway form for use by Class C builders?
When we bought a new small (24ft) Class C motorhome for just the two of us to use in exploring and camping in rough road areas, we definitely wanted one built on the Ford E450 chassis instead of the Ford E350 chassis. The E350 chassis would have handled our motorhome's weight most of the time by being very careful and lucky - but doing so right at the high end of it's E350 design specs for the braking, drive line, suspension, and frame systems. You can still find small new Class C motorhome models optionally available on the Ford E450 or Chevy 4500 chassis ... but it's getting more and more difficult.
We can confidently take our 24ft. E450 Class C carefully offroad and it always handles it well. For some improvement in ground clearance, we use larger diameter tires instead of what came stock on it. We try to "hope for the best, but prepare for the worst" when taking our small Class C out to the far side of beyond.