Maybe if it is for some reason expanded, each conference can get two auto bids. One for conference champions, and one for tournament champions. Typically both of them are either the same school or already in the tournament anyways, but as you said it could help some of the non P6.If expansion of the NCAA Basketball Tournament means more than 68 teams as a way to get more P6 schools in the tourney, that would be a bad idea. IMO the big schools get enough visibility and play enough top 30 teams to identify tournament worthy P6 teams.
For some of the other 26ish conferences, especially those that don't typically get multiple bids, I could see a couple rounds of play-in games. It is tough when teams have great regular seasons in non-P5 leagues get upset in their conference tournament and don't get selected to the NCAA Tournament.
Personally I don’t mind it how it is, but maybe an idea if it does get expanded again.