Either you go with the pure meritocracy method with promotion/relegation among the G5s. The "premier" conference gets the NY6 bid, making it a default P6 conference, and that conference gets all of the G5 CFP money. As a newfound "power" league a much improved TV deal would also be a strong likelihood. Any team that wins a regional conference and any team with a sagarin rating in the top half of CFB would qualify for the conference, regardless of history, attendance, etc.

The other way to go about it is make schools hit certain attendance and revenue benchmarks to gain access. Only schools that show they are dedicated to sponsoring legitimate football programs get in. This includes a dedicated fan base as well. So attendance, coaching salary, recruiting budgets, facilities, etc. are all part of the evaluation. In this scenario the conference would start small with a core group and grow as more schools prove themselves.

I do like the idea of adding a basketball component ala the defunct Big East. Gonzaga, Wichita State, etc. would provide a legitimacy to the conference as a whole simply due to their basketball brands. Afterall, nobody is concerned with Duke & Wake Forest playing football in the ACC. The only problem I see is the conflict of adding schools like UNLV, New Mexico, and UConn, which have good basketball brands but would be a drag on football.