SAR (search and rescue)
If the AO includes an actual MIL base, maybe have something like a detention center with POWs. Players would need to bring in a transport vic or chopper and once the gate of the detention center is open, they prisoners would board the vehicle or chopper and would have to be taken to safety, example to the terminal.
Once this AO starts, add a timer how long it takes to free the prisoners before they get executed. IF they get executed or killed by friendlies, then the AO should fail. If the prisoners die on the way to safety though, the AO should fail. (It doesnt really matter if an AO fails, since a new one will spawn after anyways.)
This would add a bit of a mission to the AO, instead of just going there and shooting at every moving pixel.