It is a common problem to overload a Motorhome by pulling a too heavy a trailer. The tow rating is the lesser of the GCWR - actual gross weight of the motorhome or the hitch rating whatever is less. For example if you have a hitch rated at 10k, a GCWR of 30k an actual coach weight of 26k you can only tow a trailer of 4K assuming you reduce the coach weight by 400# to account for the tongue weight. The point is that you cannot exceed any ratings. I have seen people towing double stacker trailers behind motorhomes all the time. However it can cause the frame to break if subjected to an abnormal stress such as a bump or pothole.