I'm just spitballing here, but would there be interest in a league like this? It could be a weekly matchup single elimination tournament (just like our regular playoff format) featuring the top teams from all the board leagues, seeded by z-scored team stats or something. We could do it based on either the previous season's results or by the top teams at the current season's trade deadline (or another obvious cut-off), as was previously suggested.
Maybe we could even scrounge together a board prize of some sort for the ultimate winner?
LoD's participation could be determined via a popular vote, but this might be fun for the 20-teamers at least.