I think the obvious solution, as someone alluded to would be to expand to two more teams and keep the 16 game schedule.
Because seriously: what's the point of divisions? Given the original nexus for this idea (that a better team will be eliminated because of division champs): what benefit do divisions bring?
As we've already established in previous threads, they're not that geographic (Miami to Boston!?), and because they comprise three extra games on your schedule, teams will get beat up by the same team year in and year out, and those teams that do the beating in a lop-sided division will come into the playoffs with an artificially good record.