I gotta agree with Deja here. Field captures are fine for the MA, but I don't think it makes sense in a historical arena. Just for thought, imagine if the LW took a field in Scotland. Wouldn't he British send in army units??? We don't have that capability in Aces High.
Increase rebuild times by a good factor. Bomb the factories and cities to increase the rebuild times even further. When one side inflicts a certain amount of damage, the side wins the "conflict." Throw up a message "Axis/Allied win the conflict" and reset the arena (maybe with a new terrain and planeset once that's occurred.) You get the same effect as landing troops on bases without the gamey effect.
Deja is right. As soon as you capture a base (or park a CV off the shore) you're gonna get a low alt gang-bang of a furball. If that's what everyone (i.e. the majority) wants (which IMO is the MA with a planeset) then enable some gooney birds and do base captures. I'll be the one taking the Spit up from a base away from the action and doing patrols away from the low-alt, endless furball.
In summary, if the majority wants field captures, enable it. This arena is for us, so it should go in the direction that the majority wants it to. I log my vote for no field captures.