I got the solution for this
Make all AI guns fire the SAME ammo that the ju88 tail guns have. And then have MANNED 40mm's in set positions, just like the fleet.
A Ju-88 gun (its a .303??) WILL kill a chute or a troop running around. Any ack huggers will know he wont gain nothing but annoying his opponent (ping ping ping.. damn there goes the paint.. muahaha).
A goon wont be able to land on its own, nor an M3 will be able to go in.
Just add a single .50 cal near the map room

Do the same thing for the fleets. Let the single ping kill 40mm and 5" be manned only and the rest of the ack be .303's. An unguarded fleet is a dead fleet anyway, AND it would also fix the need of having to literally KAMIKAZE into a cv in order to sink it.