As others have said, you'd have to have a caveat for an undefeated G5 team. Take the P5 conference champions and 3 wild cards; if there is an undefeated G5 team, they automatically qualify for the #8 seed, unless they are higher ranked. This year, that would have given us, IMO:
1. Clemson
2. Oklahoma
3. Georgia
4. Alabama
5. Ohio State
6. Auburn
7. USC
8. UCF