I was looking at the heights of things in the dats with S3D by placing nodes on top of masts, funnels, pagodas, etc, then reading off the heights.
Anyway, cherry-picking the place you set as the lock can have some goofy effects vs what RL skippers had.
Fuso, for example. RFB uses the funnel---which makes sense, it's right amidships, so is more AOB independent than the pagoda or mast. Trouble is, ONI was grossly wrong on the funnel height of Fuso, but they were dead on for the pagoda and mast heights.
Me' I'd likely use the pagoda, myself, since I'd be getting ranhges while she was hull-down.
Look at a real ONI doc:
What might make sense would be to add a few height marks (appropriately off if ONI is off from RL) for the various features. The default "lock" point can still be whatever, but the player can always dial the superstructure, etc, and use that if they prefer.