I love the idea of choke points outside town.
I never thought about the inability to shoot down from a hill top.
Perhaps the 37s on the hills tops and maybe AT near the bridges into town?
Thing is this...
V Bases have autos and manned guns. Even when you drop hangers, it is a challenge to knock down all of the manned guns, Same as port. So where ever there is a map room, should have some manned gun system IMHO. Then you have to account for not only the 8 AAAs but also up to 7 manned guns.
Currently, a single set of lancs can WF a town in a single pass if you know what you are doing. That is not an exaggeration. Then you have a single fighter make 2 passes and you are deacked.
Adding manned guns in town adds to the difficulty of taking an airfield. Plus even when the manned guns are down for a period of time, the manned guns will pop after a bit. And it would stop someone going in and deacking a town, getting it white flagged, then bailing and coming back with troops unopposed.