I think you could go to 16 teams. But since the pod system didn’t work in the WAC, I wouldn’t want to try that again. I would instead create 2 divisions as follows:
West
Boise State
BYU
Colorado State
Air Force
SMU
Houston
Tulsa
Tulane
East
Memphis
Central Florida
South Florida
East Carolina
Cincinnati
UCONN
Temple
Navy
Have 3 non-conference games, 9 conference games, plus a conference championship game.
The first 7 conference games are between division members.
The 8th conference game contains four quarter-final conference playoff games. The first-placed team in each division plays the fourth-placed team in the other division, and the second-placed-team in each division plays the third-placed team in the other division. The bottom four placed teams in each division play against their relative counterparts in the other division.
The 9th conference game contains two semi-final conference playoff games, where the winners from the quarter-final games play each other. The losers from the quarter-final games can play each other that week as well. Again, the bottom four placed teams in each division just have another game against a different opponent to finish out the season.
The winners of the semi-final games then play each other in the conference championship game. The other teams don’t play that week.
Downside is the scheduling issues it creates during the last weeks of the season (e.g., making sure each team gets enough home games, not knowing the travel destination for the visiting team earlier in the season, etc).
But on the upside, there would be a larger number of meaningful conference games, which could lead to increased TV revenue and excitement for the conference.