mkirsch wrote:
If you're getting pushed off the road by passing trucks or lines of cars, that is NOT sway. You can install both a DC and dual friction bars together, and it will not solve the problem.
Sway is when the trailer wags back and forth uncontrollably behind the truck. A single oscillation is not sway. A side-to-side bobble from uneven road surface is not sway. The whole rig moving sideways as a single unit is not sway.
Unfortunately, I don't know what the solution is, but if the rig isn't swaying, then sway control will not solve the problem.
Sway control is still an EXCELLENT idea, but for other reasons.
A hensely or ProPride is the solution to the single event occurrence. When passing rigs come by me, TV and TT stay EXACTLY where they are in the lane. Don't get me wrong, the bow wave from the truck will buffet you, but it will not move you over. 
Last year, a trip to Myrtle Beach, and I was in the middle lane on the interstate. A semi truck comes up on the left of me. I don't shift. I can feel the truck buffet just like I would without a tt behind me. When left hand truck gets up to my front fender, a merging semi truck on the right comes at my tail. I had a semi on each side of me and it was stable as a house. It was pretty amazing. No corrections with the steering wheel. None. Zero. Zip. Nada.