I think what you think is probably the right way to go, just for that reason.
I have leaned on 12 since day 1, but let's be honest, it really won't open up the door for Cinderella's like in March madness. It's just opportunity to ensure the top dawgs get in on a down year.
There were never going to be Cinderella's like March Madness because of the discrepancy in the sheer volume of teams.
But here are all the teams that would have been in a 12-team playoff at least once in the last seven years:
SEC - Alabama, Georgia, Ole Miss, Texas A&M, Florida, LSU, Auburn
B1G - Michigan, Ohio State, Michigan State, Indiana, Wisconsin, Penn State, Iowa
Big XII - Baylor, Oklahoma State, Iowa State, Oklahoma, TCU
ACC - Pittsburgh, Clemson, Miami, Florida State, North Carolina
Pac-12 - Utah, Washington, USC, Colorado, Stanford
Other - Cincinnati, Notre Dame, UCF
That's a pretty good mix of teams who aren't Alabama, Clemson, Oklahoma and Ohio State.