The NFL has 32 teams. If you want the P12 and the B1G to go to 16 teams each and have a playoff, it would be a realistic comparison.
Again, any system that doesn't start from conference realignment and in-conference playoffs will be a failed system. Build number of games played against teams in some kind of RPI type ranking into the equation and let conferences have two rounds of playoffs.
If you can develop a program that is financially viable for a major conference, develop a system whereby those conferences can benefit by expansion. If you can't make yourself financially viable for one of those conferences, then you won't be one of the big players at the end because of strength of schedule.
However, the NCAA could also appease these small conferences by requiring the major conferences play against a non major conference each year. So, for instance, the B1G plays the MAC, SEC plays SBC. P12 plays MWC, B12 plays CUSA, ACC plays BE. Set em up like the B1G ACC challenge. That would give you an idea of competitive balance across the conferences.