I wish I could rent one for a couple of weeks from Cruise America or similar business to see how they ride, handle, and also what to expect for fuel economy.
My extended (20-foot) Ford van with V10 also weighs more than this Hymer. I'd be curious if the wind affects it badly because it is so light for that size box. Having said that, I'd bet that most drivers wouldn't feel the need to add steering stabilizers, sway bars, etc. to make them drive acceptably. I doubt German engineers would likely make such a product.