I've seen literally hundreds of race teams pulling giant trailers with various RV's. The same big trailers are often pulled with Suburbans and Excursions because of the need to not only haul equipment but people as well.
For example, my friend has used an old '85 Georgie Boy 454 gas hauler since 2000 to haul his race rig, I'm sure hauling way more than rated.
So the question is not CAN it be done, but SHOULD it be done.
How exactly do manufacturers calculated GVWR and GCWR?
We know the manufacturers are gonna be very conservative with these numbers because of possible warranty issues and possible law suits.
Logically, it seems that the weakest link in the chain is what will limit the actual ability to safely tow.
The components involved are:
1. Hitch
2. Axle
3. Tires
4. Chassis
5. Transmission
6. Engine
The hitch can be upgraded pretty easily.
A unit like this "tuff tow" device appears to remove a significant amount of the downward weight from the rear tires, axles and chassis by allowing the trailer weight to be pulled horizontally by the RV versus the RV carrying a lot of the trailer weight on the hitch, rear axle, rear tires and chassis.
The transmission with overdrive off and temp gauge for monitoring heat should be designed and fully able to handle the maximum output of the engine. And if not abused with jack rabbit starts and impatient hill climbing, should be up to the task.
The engine, of course, needs to be in good working order and should not be an issue.
SO...
Where is the weak link?
Just thinking out loud here fellas.
Thanks for your thoughts.