Tow vehicle too short of wheelbase???

I think you may have too much tail and it is at risk of wagging the dog. However, you can try some things first. As mentioned, ensure 10% to 15% of trailer weight is on the hitch (there is no substitute for actually weighing the trailer and the tongue, and ensuring proper tongue weight percentage!!). Then, replace your plain WD hitch and sway bar with a hitch that has built-in sway control, such as an Equal-i-zer from Progress Mfg. (I would stay away from the Blue Ox Sway Pro for a 34' TT, some have reported sway problems with that situation). Or go whole hog and get a Pro Pride or Hensley.