It's not correct to say the rules require 2 divisions to have a championship game. The ACC plans to do it this year without using divisions, and the rules have not been changed. The issue, according to the rules, comes if you want to play 12 games AND a 13th for the FCG. You can always do what the ACC is doing this year - 11 games plus a 12th as the FCG; you can even do a version of what the Big Ten is doing: reserve the final weekend of the season for all conference matches, but don't schedule them in advance, and let one of them be the FCG (yes, that could present ticketing problems for home teams, but we'll see how the Big Ten handles it - admittedly on a small scale - this year). BTW, that wouldn't interfere with Rivalry Week, because the week in question is actually Championship Week.