I used to tow a 4,000 lb TT with a 2003 Ford Explorer. The dealer sold me a cheap Husky WD hitch with no sway control. I was going down a long hill and not watching my speed and I could feel the trailer pushing and next thing I knew, I was going 70 mph. When I tried to slow down, the trailer started violently swaying back and forth. I steered straight ahead and hoped for the the best as the trailer dragged me from side to side. I made it to the bottom of the hill and regained control and immediately pulled over. I had two flat tires on the trailer and left huge skid marks from side to side of the hill. Fortunately, there was no oncoming traffic.
My point is, if you get weight distribution, don't stop there and get sway control too. I put an Equal-i-zer hitch on it and never had another problem, even when in 50 mph cross winds. I just towed my new 33' trailer through eastern WY with 50+ crosswind warning and no problems with my 10,000 rated Equal-i-zer hitch.