New truck, New trailer, TONS of sway!

I looked up your TT and it's 35 feet long with a rear bunk house and rear outside kitchen, and comes in (empty) at over 8100 pounds. You're towing with a 150. I'll be honest and the first one say it plain out... too much trailer for your truck. No matter what you do, more than likely you'll never solve the trailer sway. That trailer has a lot of tail weight. Your truck is a single rear wheel. You're going to get sway with that set up. Simple ... you need a heftier truck. It's that simple.

Try towing with that 250 and you'll see a world of difference.