I have seen this happen before in my job. I can say this: that in the cases that I have dealt with, this same issue was due to TT being to much for the truck. The last one that I was at was a 34 footer TT with a 1/2 ton truck. When a semi passed him, the TT began to sway and he lost control. It can happen to anybody regardless of what we drive or pull with. Last year we were heading to Fort Wilderness, there was a dually blowing by me pulling a large Montana fifth wheel doing 80 plus.... stupid in my book... just saying...