Jandsa - It depends on what you mean by "smoother ride"; not to sound ignorant on my part. If your truck is hitting the bump stops/overload stop then timbrens, air bags, etc. would help. If your truck is "doing the porpoise" when going over bumps/concrete highway joints/etc, then your better option may be to look at a hitch and/or pinbox that have integrated shocks/air bag.
In 2003 I pulled a new 28' 5er with Chevy 2500HD one time before installing a TrailAir pinbox that made night/day difference. Also installed truck air springs to level the truck, but the pinbox is what gave the "ride" results.
Just a thought. If you already have this equipment, then ..... never mind!