I liked Air Warrior's thing that a captured base would rebuild itself in time (just like AH but the ack would not come up instantly), but you could speed up the proccess by gooning in supplies.
In AH, I think it would be best if once a field is captured, only the MANNABLE acks come up (aka those 10 grunts that captured map room are now manning the guns) and have new loadout options for the Goons (and hopefully, Supply Truck if HT is nice to add one):
Option for Goon:
Troops
AAA (aka guns and ammo to bring up 5 AI guns instantly)
Supplies (each goon with supplies would cut down rebuild time of hangars and barracks by 25%)
Fuel (Each goon with fuel would cut down fuel rebuild by 25%)
Ammo (same as fuel, but for ammo).
Same options for trucks/Ducks (amph.) if they ever introduced.
Then players could take a field, have a fair and square chance at defending it with mannable ack guns while the AI rebuilds AND have the option of ferrying in a convoy of goons/trucks/ducks to bring it up quickly (plus giving the other side a plumb variety of helpless targets..buahahhaaa

)