The best motor/transom height match is the one where the water flow at speed skims right under the small upper plate while boat runs on plane on calm flat water cond with trim remaining at neutral.
For that have a light mate to pull his head out middle transom and visually check at which lower leg height is water flow passing by, will instantly know if in need to raise or lower a tad the motor to achieve that cond or as close to it as possible as the transom holes don't play by the militer when raising or lowering the motor on the transom.
The setting mentioned on all Owner's Manual are just references on a dry motor/transom installation which most times doesn't work as expected. When boat is on its way, it's a differente wet story.
Once dialed, if deck weight is evenly distributed, motor runs towards its full wot rpm range with a maximized prop you won't need to move the trim from neutral position. A motor running towards its full rpm range as loaded makes a day/night planing difference.
BTW, have 20 years experience doing so on my own and friends different type of boats with excellent results.