Maybe a mechanic could be made where if an area is outside the range of the airbase you're stationed at, but within range of another, missions could be flown there at the cost of say efficiency. But as a computer scientist I can tell that this would increase the complexity of range calculations quite significantly. That said, I don't know how much these affect the speed of the game as is (ten times nothing is still nothing), and there might be some cool trick that allows it to be done much faster.
Had a game recently where I had tons of planes, but no way of putting them in the sky because I couldn't supply them. This might have alleviated said issue, or maybe I just need to up my supply game? That said, things seemed to have bugged out with province control so maybe the game was to blame. For context I was playing as Japan with the "Soviets" as my puppet, fighting the Axis' Russian collaboration government along the border between Europe and Asia.