Aero units (Not VTOL's, but true boom-'n-zoom fighters and aerospace units) are a tough problem when it comes to integrating them into ground battles. That is true not just for AS, but for every BT system I've tried. I am, as I've mentioned before, not a fan of the current AS aero rules. The air-ground interaction is functional, but there are a lot of places it falls flat for me.
When I use aero, which I admit isn't super often, I usually don't try to make it a core part of the battle. I usually allow two or four fighters a fly-over on certain turns (2 and 4, 3 and 6, something like that) and don't use bombs. I divide whatever their PV is by two or three, depending on how much I think they will actually show up, and use that for rough balancing. I don't even try to run an air battle simultaneous with a ground battle.
I know that isn't terribly helpful, but the current aero system has been far enough away from fun for me that I haven't really wanted to spend time tweaking it to make it more to my liking. Scotty probably has a better answer!