…a set of airwar rules, played with model airplanes, that doesn’t require positioning the models in their real-world spatial relationships (pointing at each other) in order to execute combat.
Correct, because I don’t see the need.
Do I understand that you still want the models to physically move up and down on sticks? Seems…inconsistent. Am I missing some point?
The (broad) height difference of elements in an aircombat game are as relevent as, say, an East-West difference in elements in a ground combat game.
The indication of those differences can be done in many ways (dice on a stand – be it a Wellington bomber or a Wellington command) but there is no reason to presume that one method of location is any better than another simply because a different dimension is involved.