Just some thoughts, now that I'm back for a while:
If it's all that important to populate the island with monsters, then we should be able to preserve the "front lines" theory and just release them on the entrance square by the port. Since it's not all that important to go north right now, we can always go west from the square that's northeast of the port later, and not have to use the port square as a front line again.
But I don't vote for starting monstology yet, because I'm not convinced that it's necessary.