The tires are more than capable to handle heavy loads. I have a transit 350 srw with payload of 4100lbs.
That keeps the GVWR at 9500.
When you hit 10,000 lbs a lot of states get into cdl territory and nobody wants that. The drw transit is 10,000 lbs so not much different in capacity.
As far as pickups go most aren't used to haul heavy and extra cabs, leather, sound deadening, and options weigh them down a lot.
Many dually trucks are derated to 9500 to keep them out of cdl territory.
A standard sized gooseneck trailer is usually 14,500 GVWR so that pairs nicely with the 9500 truck to keep you under 26,000 which is cdl required.
RVs have no cdl requirements but they're not going to build special vehicles outside of the class A/B formats just for that purpose.
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