I hear a decent amount of people on here saying there should only be two divisions. Why not try a tournament that way? It can get expensive to run tourneys (hence why I don't TD very much) but you might be able to get your club on board. Especially if you sell it to them as being something unique, something they can put their stamp on.
There ARE events that do this. They are few, but they almost always fill up because they are well run, quality events. Those of you who are of the aforementioned opinion should try it out on a B or C Tier scale. See if you can still get a bunch of people to sign up.
Push your idea forward. See if it works.
Maple Hill Open Ams is a C-Tier with just two divisions: men and women. It didn't completely fill this year, but it has in the two years prior.