Instead of using a minimum number of aircraft, perhaps try a different approach. Say you give 4 attack objectives to a side, and you want the side CiC to field some buffs. In the objectives you can state that at least 2 attack objectives can only be hit by buffs, i.e., no JABO fighter can touch that objective. The other 2 attack objectives, the CiC can send buffs, JABO, or a mix of both. The CiC can pick which of the 4 objectives are buff only targets.
You can approach it from the other angle where you say out of 4 attack objectives, a max of 2 can be JABO targets. The objectives can say there are only two available groups of ground attack fighters for this operation, but four available bomber groups. That would mean the CiC could send bombers to every target, and heavy fighters to two of the targets for insurance if they wanted.
You get buffs in the air, but the CiC doesn't have to worry about the actual minimum number of pilots in the buffs. Yeah, the CiC can put a 4-6 squad in the buffs, but if those buffs fail, the side won't get any points from those objectives.
