OP, been there done that, except we lasted about 30 miles and a half hour. Some trailers for many reasons create chucking forces. One major factor is short length. Not much you can do to change that.
Let's see, truck doesn't chuck when the trailer is not hooked up. There is chucking when the trailer is hooked up. I know, let's blame the truck. The truck is not causing the chucking.
The hitch is not causing the chucking. It is just transferring the chucking energy to your truck frame. If you are using a solid joint hitch (Andersen) you might as well have your drivers seat bolted directly to your pin box in terms of comfort. Chucking energy that makes occupants uncomfortable has a pathway that goes from the trailer to the pin box to the truck frame to the cab to the seats. The truck's suspension is not part of this pathway. Truck shocks, air bags, different leafs or heavier trucks will not alleviate your problem. Your trailer is creating the chucking forces.
Your solution likes at your hitch joint with the goal of keeping the chucking energy your trailer is generating from reaching your truck. This generally entails an air ride hitch or pin box which converts chucking energy into heat energy by compressing air and radiating it into the atmosphere. I can guarantee you my chucking was as bad as yours and my solution was an air ride hitch. No more chucking. I just completed a 7 hour tow today from eastern Oregon. The road was **** with many bumps and heaves. We still felt the jolts when the truck hit the bumps but we felt nothing when the trailer hit the same. It just bounces along back there (still creating chucking forces) but none of it gets into the cab of the truck. The heaves are still an issue but no getting around those.
My Trailer Saver TS3 was designed to remove chucking forces. It works splendidly and is the reason I still have my 5er and enjoy towing towing it. It was expensive but is worth every penny.
