Perhaps, air to air kills, even those from a gunner seat, should toss those perks into the 'fighter' category while kills with ordnance (to include players, buildings, etc.) will lump them under bomber perks?
This way you don't run into the issue of bombers farming perks for fighters, and you can still earn some fighter perks for dogfighting in a B-25 or some such.
If such a thing were to be implemented, I imagine GV perks would still be implemented in the same way they currently are.
Thoughts?