Bit of a counter-idea (just musing, no means am I even considering it as a game feature yet... just fun to think about):
What if Fighters have as sole reason to damage bombers or other fighters, while bombers sap a random 1HP from a unit every turn?
So in protracted wars, it'd be a bit of a battle trying to catch fleets of bombers trying to damage split armies, a sort of shadow war next to units.
Haven't considered the implications, but neat to add such a thing...
I love big ideas like this, even if they don't always make sense for an old game.