So I was bored at work and spent a few minutes trying to visualize what four conferences of 80 teams would look like. I picture each conference having two divisions of ten teams, or four divisions of five teams. Play everyone in your division, some from the other divisions and a couple noncons. This includes all P5 teams, plus ND and several G5 teams. There are many schools that would scream bloody murder about this, but in some ways, I kind of like it. Reasonably balanced, makes some geographical sense, not too many "reaches" as far as what teams are included.
Western Conference
West Coast division: Ore, Wash St, Cal, USC, Ariz
Pacific division: Ore St, Wash, Stan, UCLA, Ariz St
Mountain division: Utah, BYU, Boise, CU, Col St
Heartland division: NU, Iowa, ISU, KU, KSU
Southern Conference
Lonestar division: UT, ATM, BU, SMU, UNM
Southwest division: OU, OSU, TT, TCU, Hou
Deep South division: Bama, Miss St, Ark, LSU, Mem
Gulf Coast division: Aub, Miss, Mizz, Tulane, So Miss
Eastern Conference
Atlantic division: FSU, GT, Mia, Wake, Lville
Southeast division: Tenn, VT Kentucky, Vandy, ECU
East Coast division: UGA, SoCar, NCSt, USF, UCF
MidAtlantic division: Fla, Clem, UNC, Duke, UVA
Northern Conference
New England division: PSU, Cuse, BC, Conn, Rutg
Northeast division: ND, Pitt, WVU, UMass, MD
Great Lakes division: Mich, Mich St, Illinois, NW, Cincy
Midwest division: Ohio St, Wisc, Minn, Purdue, Indiana