I think school staff--game administrators and coaches--should take point on crowd control, not the game officials. Their attention needs to be on the field, for safety as well as fair play.
A coach can set the tone for crowd behavior, sometimes without even realizing it. It seems really easy for some coaches to incite the crowd, which can turn ugly. It's also pretty amazing how much affect a "thanks, but tone it down" gesture to the crowd can have on otherwise well-meaning unrulies--often without the coach even needing to turn around and take his eyes off the field.
