truck ride

Slap on a set of air bags and air them to 30psi LOADED. Report back.

Try an air ride hitch.
Have you run it across the scales yet? Could be light or heavy on the pin.

Airlift bags for the rear and Riderite shocks which are air shocks on front.

Bouncing is a very vague term when trying to diagnose suspension.

Is the vehicle suspension cycling multiple times through full travel after hitting a bump? Is this front rear or,both? Or is something else happening?

Is the truck bottoming its suspension? Or is the suspension really stiff and you are feeling weight transfer front to back in an uncontrolled manner?

How is your ride height?

If the above is more like, this describes a lack of rebound damping in your shocks. Airbags, which really just add spring rate, aren't going to fix that.

What kind of shocks did you put on?

Lots of questions. Few answers. But nothing unfixable here.

Welcome to the forum. An air ride hitch or air pin box will dissipate most bouncing forces before they reach your truck. These would be bouncing forces from road imperfections and small bumps. You still have almost a ton and a half of weight in the bed of your truck so large bumps and heaves like railroad tracks will still be felt. Can't hide from that.

If your trailer pin is bouncing on smooth roads then there are other issues. Where I live smooth roads are very rare. Make sure your spring shackles and hangars are in good condition. Shocks on the trailer are a good add.

I installed a set of Torklift Stableloads on our 3500 and it made a big difference in ride quality. They activate the overload springs quicker. Took out a good bit of the bounce we were getting with our truck and FW.

PIN weight, make sure you have at least 20% pin and more like 22% to 25%. Then work on making the 5er tow smooth and level, I have near zero "chucking" only. Little on really bad roads.