First - when you are hitched up, are both the TV and TT level? If not, you need to adjust the chains to make it so.
Second: Your TV is likely too little truck. I was towing a 26' RV with a Jeep Commander and had a similar experience: When a semi would pass, I would get sucked over towards it as it began to pass me and then pushed away as it went by. Same with wind. Sounds to me like what you are experiencing. The only solution is to replace your TV, unfortunately - which is what I just did. The difference is amazing.
Let's also discuss what you are experiencing versus sway. Sway is when the trailer begins oscillating side to side, increasing with each swing - much like someone on a swing set. Left unchecked, it will eventually cause the trailer to jackknife. What you describe - and what I experienced - is more of the TT moving the TV due to inadequate weight/wheelbase of the TV. Imagine a wagon being pulled by a husky versus a poodle and the effect that the wagon could have on the dog as it is pushed side to side while in motion.
If this is the case, there are only two ways I found to mitigate it:
1. Minimize the speed differential between you and other vehicles. A semi passing you doing 15mph faster and one doing 1mph faster is dramatic. Of course, you might not want to drive that fast.
2. Reducing your own speed to where the TV is more easily controllable - which, of course, will affect you when semis pass as noted above. This is more helpful when it's windy.
We never went very far from home with the old TV due to this issue because the drive was that stressful. I cannot imagine driving from FL to Canada under those conditions.
My thread about these issues:
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/27938656.cfmNote that I tried most of the offered suggestions to no effect. Replacing the TV was the only thing that solved the issue - and by solved, I mean that it reduced it to insignificance rather than eliminated it. When a semi passes by doing 15mph faster, I now feel a VERY minor tug and go "Ah, a semi!" Instead of "HOLY ----" and freaking out.
One last note: I had a terrible time seeing where vehicles were to my rear and knowing if it was safe to change lanes, so I installed a backup camera on the TT. One nice thing about that was that I could see that I was NOT experiencing sway in this condition since the rear of the TT was not oscillating - after the large vehicle would pass, the rear of the TT was straight and not moving side to side (the lane markings didn't move in the camera picture).
