I had some chucking, and went with a MorRyde. It helped but didn't eliminate it. Added 5100's and now it's pretty good on all but the worst roads. I did a nice 1400 mile loop about 5-6 weeks ago and overall it was mostly smooth. The few times I had some chucking it was very limited time wise. All in all I would have no problem doing a cross country trip with the way it tows. If I was full timing or doing 6-8000 miles a year I would probably look into a pin box that eliminates any up and down as well as front to back. For our 4000+ miles a year I'm pretty happy.
FWIW I tried towing it as it's set up with 70psi and 80psi in the rears. I found that 80psi was the better of the two.