I work with a Catholic school system. Parents are strongly encouraged to participate in some volunteer manner, such that thousands of them volunteer. Everyone of them attends a seminar about protecting children from abuse, and they all pay for their own background checks (local and FBI). If they become inactive for over 6 months, they have to get a new background check. Some private companies offer
national criminal background search for lower cost with instant results, but they do not qualify for the School system, which requires the FBI fingerprinted background check.
So, I'm betting that there will be plenty of Officials and Referees willing to get a background check and keep the league running properly. The procedure is pretty simple. Get your fingerprints taken at you local sheriff's office. If they scan you fingerprints electronically, then you just pay and it's done. If they take your fingerprints with ink on a paper card, then you have to mail it into the FBI and to your State criminal records bureau.