Now you can use automatically generated distributions with world-borders in default Bukkit and with ChunkyBorder installed. Example:
You use ChunkyBorder, you set the border to a star with some arbitrary size. If you set the distribution in your rtpSettings file to world-border then the distribution will be large enough to cover the area. Oh, and since there is support for border regions aswell, you will never have anyone get teleported outside the world border, even if it is a ridiculous shape like a star.