The rules when I played at MSU for co-ed football were relaxed about number of females on the field, I think only like 2 of 7 or something. But there was no running, and all completed passes had to be at least 5 yards down the field. But you had to have two passes completed that involved a female to get a first down. Trying to get 50 yards in 4 plays was tough, so the good teams had the best females, because they had a decent shot of picking up first downs. BUt the BEST teams had female quarterbacks. You couldn't possibly cover all 6 receivers for 3 out of 4 plays, and they would just dink and dunk you down the field, picking up a first down every other play.