Hey, now we're making progress. 100 feet is VERY low, I think tree's would become an issue at that point, maybe 250 feet with no auto pilot would be fine. I'm not sure how you would limit the aircraft though, I think hordes are just part of the game whether high or low, and your not going to be able to limit them.
I was thinking though, what if we had an "ENY" limit? You could only have so many low-eny aircraft in a mission, that way we don't get ridiculous aircraft in the mobs. But if there were less pilots, you could have better aircraft... Would make sense to me.