Another alternative would be a similar setup to Charming Town, where we have a board and each area in the RP World has its own topic, so people can go in and out of topics as they move around the island. This at least makes it easier to engage in battles between the two sides, as well as providing more freedom for people to move between groups, since some people could very much hate each other and would rather go off with the first friendly group they come across.
To make organization easier, there can also be a "map topic" which basically pinpoints where people are. It would need to be updated by everyone when they move around. Though I think it would be very possible to manage.
The main disadvantage is that we would have to have most of the landscape planned out so we know where each battle is taking place. We already have the bases for the two sides, on opposite sides of the island. And also a way to decide time is pretty important, to prevent random teleportations from one side of the island to the other.
Other than that, I have faith in this idea, although you guys have some excellent ideas too. Hope we can get this off the ground soon.