I have just completed resetting my hitch after having some rear suspension work completed on my '75 Cadillac - - raised the ride height by nearly 2". In addition, the hitch was set up for my '64 Airstream that needed 18.75" rather than the 18" for the Minuet that I am preparing to tow with the car. I found the following "pdf" file from Reese to be invaluable in the process of making these adjustments:
Reese Hitch Head Adjustment Directions
Basically, what I learned through following these instructions was that the suspension on my Minuet has settled resulting in a level ride hitch height of 17". Following the directions in the "pdf", I set the hitch height to 18" (measured to top of ball the additional 1" is to compensate for tow vehicle squat as per Reese directions). After reading these instructions, if I were setting up the hitch on my Suburban and I could get sufficient drop, I think that I would set the hitch height to 17" as the Suburban doesn't squat at all when the Minuet is hitched to it and 18" is resulting in a nose high attitude for the Minuet
The result is a very smooth towing experience with the Minuet and Cadillac combination.
Good luck with your project!