All of the above are at least partially correct.
Part of the draw of the SSWC is that there is no controlling body. Doesn't seem to need one. Does fine without. Every year at SSWC there is a contest (volleyball, air guitar, beer pong, etc) to determine the nationality of the subsequent year's race. The torch is passed to the representatives present (yeah, whatever yahoos show up that year) and that's it. That simple.