If you flipped your thoughts over so upper ring to lower ring and vice versa you'd be there 
there's different height "zones" that a particular springs can give you. If you're having to relinquish preload to below zero then your spring is too short. Which is usually the case where larger than designed wheels are concerned. Leaving preload at a set amount, or increasing where necessary and using your lower rings to vary height prevent the problem below (assuming correct springs are used)
All springs are designed for the control of sprung mass and as such the coilover is designed to give control over the way that mass is distributed and controlled. Unsprung mass, such as the hub, is controlled by damping primarily. Height is a personal opinion thing too, but can still be balanced whilst higher up but if you set it so that you just touch your bumpstops at max cornering speed/ lateral g-force then that's the correct amount of bump travel. But is only found by measuring with data logging potentiometers and a bit beyond our balancing
I could keep writing really long replies but until you see it, it'll be difficult to understand what I mean. At the moment you're using you coilovers in a part threaded manner
I'll try do a guide to see if it'll help with a few pics and figures all this is avoiding springs rate, compression speed vs force, unsprung mass, damping, alignment etc etc. Corner balancing is only our base setup
He got that design spot on and as I've said before that's the best design I've seen to date
We'll arrange something one day I'm sure. Have a small weekend trek with an event to follow afterwards. That way I wont forget as you can remind me
You bring the white board, I'll bring the pens
