Use college graduation rates coming out of private or public as the baseline measure of setting up the grade based league. That being said, just let public school kids play -1 grade if they want. My private hs school kid is playing the grade it says on his report card. My kid's team will just pick up a couple public school studs to make his team better than it already is, and let those 2 or 3 kids explain to coaches why they are playing in that league, instead of the other 20 kids that are playing exactly the grade their report card says, as authorized by the State having jurisdiction. Oh, you don't want to have to do that, well guess what, either do I, so go pound sand.
