I can't tell you the highest placing Southcoast team, but the final four teams were from other leagues. I left when the final match was about to start because the drive back from Vegas on a Sunday is awful and I needed all the time it took (about 7 hours).
There is a complete recap and final standings for all South Coast teams. From the Home page go to Events /2008 8-Ball Southwest Challenge.
Each of the final four teams was from a different league area. 3 out of 4 had never won before, with the 4th team having won back in 1998 (back when it was just a little tournament in Sam's Town).