Gunner, expand your horizons bud! This new ruling is ripe for "outside the box" thinking if anyone would go there.
If I read this right you can have a CCG if: 1.) You play a round robin, 2.) You have a process to rank CCG opponents. 3.) You can still have divisions as long as play is a round Robin format. 4.) Rematch play is inevitable, but managable.
So what IF: B12 splits into 2 divisions of 5 but still plays a round robin. Utilize a modified English Premier League scoring system to rank teams within the division: 2 points for a division win, maybe 3 outside division, etc. Come up with something that represents strength both within and outside div.
The rematch is inevitable, but you get teams that were powers both within and outside the division. Also makes expansion easy if it come to that. B12 needs something to separate itself from the pack. Maybe a little creative thinking is in order.