Below is a link to the Winnebago brochure for our 2005 Itasca Class C.
The last page shows the layout of the internal aluminum framing within the coach walls. Looking closely to see the aluminum framing of the cab overhead, I do not see how the cab overhead structure is going to move up or down, or left or right ... in any motions separate to those of the coach's main living area structure.
Hence, how is the cab overhead going to get jostled around any more, or differently, than the whole coach when traveling?
https://www.winnebago.com/Files/Images/Winnebago/brochures/2005/05-Spirit-bro.pdf(However, a forward facing cabover window is really going to get blasted by water when traveling in a rain storm - along with the cabover clearance lights!)