You could play three crossover games each year, giving you eight games. These games could be scheduled on a rotating basis on a two-year basis. In other words, teams A, B, and C from the South would play teams A, B, and C on a home and home basis in years one and two. In years three and four, the schedule changes. You could also use a system similar to the PSAC where crossover games are scheduled based upon previous season s records.
Theses are just two suggestions as to how to handle crossover play.
If you go to three crossover games then you are at eight games, with either two or three games to schedule. If you want to crown a true conference champion, this can be done in week eleven, with all conference teams getting a game. In odd years, The North Hosts the Championship game as well as games between third and fifth place teams. Alternatively, you could have all games in the South one-year and the North the next. Using the above scenario, there would be two open weeks to schedule.