How about this for a possible solution to current and future division imbalance: floating divisions.
1. Add BYU, Utah, TCU, and Air Force to the conference. (if necessary, only for football and not other sports)
2. Create 4 roughly equal half-divisions:
north-NU, ISU, MU, CU
central-KU, OU, KS, OSU
south-UT, TT, aTm, BU
west-TCU, BYU, Utah, AF
3. Divisions are made of 2 half-divisions and swap every 2 years between
north (north and west) v. south (central and south)
southwest (south and west) v. classic (central and north)
4. 7 games are played within division and 1 game is played cross-division against a teams conference rival if the team has one or random team if not
OU v NU and KU v MU in north v south years
OU v UT in southwest v classic years
5. Teams with the highest in-division records go to championship. Winner in head to head for tie breaker. Only in the case of 3 way ties are cross-division games counted.