A few constraints that immediately come to mind, and my initial reactions to them:

- Minimum number of games given to each team? I figure if at all possible all teams should be able to play 8 games in a day.
- Maximum number of non-finals rounds? I'd think it would have to be 10, given that many high school sets only have 12 packets.
- Minimum number of prelim rounds? I'm not as sure about this one, but I would think for high school events you wouldn't want to eliminate teams after 3 rounds.
- Minimum number of teams per bracket to remain in finals contention? I figure that would ideally be two (or if necessary one with wildcards), but I'm not sure how feasible that would be for certain formats