Currently the closest you can get to spawning at the equator of a world on world creation is on the "hot" starting climate. That makes it impossible to create a perfectly centered world with poles at the south and the north on a limited size world. The "hot" starting climate spawns you at around 17'N and on a limited size world where the equator is half the size of it, it makes the pole positions not be symmetrical. A simple start option on world creation to start at 0'N would fix unsymmetrical limited sized worlds. It can just be named "Equator" or whatever. It would be nice to be able to make the north and south poles the exact cut off of my world but it currently can't be done.