At first I thought the same as you "not a big issue in softball" however, in the last 6 years Marist has won two state championships, and the other 4 years, they lost to the eventual champ, twice in the championship game, once in Semis, Once in super-sectional.

I really don't know what you do here, maybe let them go beat up the other private schools in a separate division? Ultimately they are not playing by the same rules as the rest of the field, so how can you validate any of it? Its simply not a fair playing ground.