If you are going without WDH, then you need to estimate how much sag your suspension with have, and compensate. If TW is 500 lbs, get 500 lbs of people standing on the bumper, and measure the height from the ground to the top of the square opening in the receiver.
Hitch height (loaded), minus coupler height (while level), minus ball height (not including threads), equals the amount of drop you need in the drawbar.
If you have a WDH, then you should follow the instructions provided. It will come with an adjustable shank, so it's part of the setup.
My Equal-i-zer instructions say to start setup with the ball height equal to the coupler height (no compensation for suspension squat. This, of course, is because the WDH will couteract that squat.
thebrakeman ('70), DW ('71), DD ('99), DD ('01), DD ('05)
2004 Surveyor SV261T (UltraLite Bunkhouse Hybrid)
2006 Mercury Mountaineer V8 AWD Premier
Equal-i-zer WDH (10k), Prodigy Brake Controller