Just a thought about the perpetual mission problem.
Would it be possible for a mission to have a specified target, a field or other strat target. Offensive missions could be scored on how much of the target was destroyed or if the base was captured.
CAP missions would be setup in certain sectors, perhaps a 4 sector area. Planes in the CAP mission could earn perks for killing planes in that area just as now, and there would be a small bonus if the strat in their area was undamaged for the duration of their mission. A multiplier could be used for strat damage so that a little damage might lower the % and heavy damage lower it further or even eliminate it.
This might give an incentive to pilots to set up defensive missions and try to interdict incoming planes. Also I would suggest that only pilots that land from the mission be given the mission perk multiplier.