Non 5'er----yet

As far as hauling and towing I think you can haul a much larger load than what the factory says you can. Limitation is tires, but legally you could be in a world of hurt. If you cause a death or injury to someone in an accident you could even be criminally liable even if the weight of the rig had nothing to do with the accident. Lawyers are like that ya know!

Respectfully this comes under......Internet myth.
Every LDT truck in commercial service on the road pulling heavy trailers is carrying weight above the tire placard payload rating or a GVWR number payload rating and in that industry your scenario is a non issue so why is it just RV websites where this myth pops up from time to time.

I'm a long time OOIDA member and a forum member.
Over there the advise given by their lawyers and life time OTR/LTL owners and operators is do not exceed steer/drive or the trailers axle/tire load rating numbers or a gross or gross combined operating weight. If those weights are exceeded and the vehicle(s) was responsible for a accident then the truck operator can face a civil suit/vehicle and load impounded/loss of CDL/jail time/etc.