If divisions didn't exist you could add Cincy and go 4 + 5/5. But even then Notre Dame and the SEC screws that because Clemson and FSU won't want to play 11 P5 games per year.
I hope the end game is 5 conferences of 16 teams with 4 divisions in each conference. That allows you to play everyone home and away over 4 years with 10 conference games. The P5 becomes D1A. The G5 and some of the top FCS schools form D1AA. And the remaining FCS schools become D1AAA. There would be plenty schools in D1A with 80 in total. OOC games become much more interesting too without the G5 and FCS teams to pad up on.
SEC
North- Kentucky, Mizzou, Tennessee, Vandy
South- Bama, LSU, Mississippi State, Ole Miss
East- Auburn, Florida, UGA, South Carolina
West- A&M, Arkansas, Oklahoma, Texas
B1G
North- Michigan State, Minnesota, Northwestern, Wisconsin
South- Illinois, Indiana, Ohio State, Purdue
East- Maryland, Michigan, Penn State, Rutgers
West- Iowa, Iowa State, Kansas, Nebraska
ACC
North- BC, Miami, Notre Dame, SU
South- FSU, GA Tech, NC State, Wake
East- Clemson, Duke, UNC, UVA
West- Cincy, Louisville, Pitt, VA Tech
P12
North- Oregon, Oregon State, Washington, Washington State
South- Arizona, Arizona State, UNLV, Utah
East- Colorado, Houston, Oklahoma State, Texas Tech
West- Cal, Standford, UCLA, USC
B12
North- Boise State, Colorado State, Kansas State, Wyoming
South- Baylor, New Mexico, SMU, TCU
East- Memphis, UCF, USF, West Virginia
West- BYU, Fresno State, Nevada, San Diego State
That leaves behind the states of Connecticut and Hawaii, plus the service academies.