The reason for the playoff is to find the true champion or just entertainment? It is glaringly evident that there are never one ,two or four teams that separate themselves from the rest of college football. We end up using this thing called the " look test" to judge who has a chance to " win" the title. No, that is not a good way to find the champion in any sport.
I think anyone in the top 10 can beat anyone else on any given day so I would make the field 12 with byes to the top 4 conference winners and a home game for them after the bye. That gives plenty of incentive to win your conference and not rest players.