Disclaimer: I’ve always liked your CFP ranking system, even if I’d disagree with a particular order some week.
Obviously, 4 undefeated P5s make it, but where do you put the loser of tOSU/UM? The only way your #6 happens is a tOSU loss to Minnesota and/or a UM loss to Maryland, with a losing team winning out.
I feel like your #6 would be more realistic as Big10 once-defeated division runner-up, something that’s existed in years past for the SEC with two playoff-level teams in the same division. I think losing to a top-3 team would get preference over most one-loss conference champions, but it would probably depend how close the losses were.