milo,
I guess my idea assumes bowlers have an ounce of integrity, and would join such league for a challenge.
Everything is a potential nightmare with bowlers that whine about things that may, or may not, happen.
If a ball cracks deal with it. If a bowler gets hurt trying to make Ball A do something it can't do, you deal with it.
Every league has a board of directors (comprised of team captains) that can meet for 3 minutes and handle things.