Making sure that the trailer height (from ground to bottom of frame) is about 1" lower than the ball height when not connected. Measured between the TT axles on level ground and same with the ball.
IIRC, in my case the height between axles was 23" and the top of the ball was 22" creating a low point in which the WDH was useless and caused my trailer to sway like I was getting hit from nasty crosswinds when there wasn't any. Highway speed. The dealer lifted the WDH ball to 24" and problem solved.
Also that the WDH hook up brackets are equidistant from the coupler.
The dealer that I bought from didn't have it set up properly. 2" differences between the hook up brackets- right side @28" and left side @30".
A good idea is to make sure your front wheel well/fender is riding at the same height after every hook up.
I hope this made sense.
2011 Nissan Xterra
2016 Rockwood MiniLite 2306 First ever RV.