Well, you limited it to 20 people, and most of the seats are full. We're ready to go!
Actually, there aren't any plans to endorse individual race series except for the Weekly, which GTPlanet hosts and has proven to be highly popular. GTP will probably 'sponsor' a team for the Board Challenge 5 if it gets organized, and so there will be a team qualifier of some kind for that.
But while I agree your USTCC series looks fun, we don't really want to get involved with picking more series to promote as "Official" because that opens a whole new issue of deciding which to back and which to not.