I think divisions could still work of 2 divisions of 5 teams. But, it would be way better if it was for 12 teams instead. Here is an idea that could or could not work for 12 teams:
Week 1: non conference
Week 2: non conference
Weeks 3-7: Divisional Games
Week 8: Protected rivalry games
Week 9: SIAC Championship Game + Champions Week (Big Ten used this format last year)
For 10 teams currently,
Week 1: non conference
Week 2: non conference
Week 3: non conference
Weeks 4-7: divisional games
Week 8: Protected rivalry games
Week 9: SIAC Championship Game + Champions Week
Obviously, this is a big question if this format could work and what schools would agree with this format. As I don’t think there are no conferences that play an conference championship game in Indiana (could be wrong). But it’s an interesting proposal/concept, if the SIAC decides to expand to 12 teams or switch to divisions.