Long Box vs Short Box and slip hitch for 5th wheel

I've had a shortbed pickup and one of the old fullsize ramchargers used for towing TT and cargo trailers. I felt the ride on both were choppy especially on highways where the cement was poured in sections or other bumpy roads. I equated this choppy ride to the short wheelbase.

For the past 30 plus years I have had many longbed pickups and find the ride to be a lot smoother both empty and when towing a 5th wheel or TT. Plus I choose dually and find the towing to be much more stable than a SRW truck.