I have never seen where a truck manufacturer recommends a lower tire pressure based on no load. In my own experience the tire manufacturers' charts result in underinflated tires with uneven tread wear and shorter life.
Underinflated tires will also negatively impact road handling and stopping distance and the greater amount of sidewall flexing will make them run hotter - this was why the Ford Explorer's were experiencing blow-outs and killing people.
Anyone who has gone up a load range with the tires on their truck has experienced better handling from the stiffer tires. The offset is a harsher ride.
A 200# fiberglass cap will do a lot to smooth out the ride on a heavy truck when there is no weight on the hitch. You could achieve the same by putting a couple bags of sand in the bed.
When I have looked at trucks on dealers' lots I have noticed wide variations in the payload ratings of the trucks based on the tires that were provided at the factory. I have seen factory supplied truck tires with load capacity ratings from 2200 up to 3200 lbs. on heavy duty models.