Ultimately, you want the finished, WD setup to have the trailer level, to a tad low up front. That's hard to determine with measuring unloaded heights, but that will get you close enough to get the initial setup done.
Hitch it up, take it for a run and decide from there..
I towed my trailer for a whole season before I decided to lower my hitch head a notch. Towed much better after that.
Not gonna happen on the first time for the most part... So, just gotta pick a setting and see how it works for you and adjust from there..
Good luck!
Mitch