Your DrawTite is made by the same company that makes Reese. Draw Tite also offers the Dual Cam sway control which can be added to your existing weight distributing system. It is all the same stuff with different names and part numbers on it.
http://www.draw-tite.com/content/pro...ID=1655&part=0
(For those that might doubt the above, bring up the Reese and DrawTite websites side by side and start comparing items. They are all owned by Cequent who also owns HiddenHitch and several other brands.)
FWIW, one friction sway control manufacturer recommends that friction control is only useful on trailer up to 25' in length or so. Longer trailers have too much fulcrum power on the hitch for the friction controllers to work properly.
For trailers as large as yours, the preferred sway control is Reese (or Draw Tite or Hidden Hitch) Dual Cam, the Hensley Arrow, or the Pull Rite system. There are merits to each. The Hensley and Pull Rite are significantly more expensive but they do work. There is endless debate about which of the three systems is best. What I have never heard is anyone claiming that their <fill in the blank> did not work as expected.
Since you already have an investment in a DrawTite WD system, it seems to me that adding the Dual Cam to your existing gear would be the most cost effective approach.
One other point. Many dealers and trailer shops will give you trade-in credit on individual pieces of your hitch system. For example, if your trunnion bars do not have the detent needed for the Dual Cam, they might well take them in trade on the proper bars needed. And, they might have used components to offer to you at a reduced price. I have purchased used hitch system components many times and never had a problem with any item.