Quick idea:
3 divisions of 6 teams (We'll call them A, B, C)
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If I'm a team in A, I play:
5 fellow Div. A foes
2 from Div B and 2 from Div C
Every 3 years, I'd have played all Div B & C teams once.
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The conference would map those pairs out by random, luck-of-the-draw every 6 years (3 years, but home-and-home).
Division ideas:
West: USC, UCLA, UO, UWarsh, UNL, Iowa
Central: Minn, UWmad, ILL, NW, IU, PU
East: UM, MSU, OSU, PSU, MD, RU
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Or you could mix them up a little and go with something like Legends, Leaders, and Poachers.