Yes, that would be a great start. USlacrosse also issues supplemental insurance for most (all?) events that I have been to--they could simply refuse to insure events that don't comply.
In my experience the insurance just askes the organizer to require each player is/has a US lacrosse # and waivers are filled out, but as a player if you do not have them you are still able to run the event without being liable. The onus is on the teams to provide you not for you to demand to collect it. I wish all coaches knew that one. Because truly under law if their player causes an issue or is hurt the coach is the responsible party.
So all you daddy coaches beware.
