http://www.tirerack.com/tires/tests/...y.jsp?ttid=172
Dunlop ZII, Bridgestone RE11A, and Yoko AD08R are likely more DD streetable than the BFG Rival based on wet grip. I'd probably lean more to the RE11A and AD08R if hydroplaning resistance is a concern.
MPSS are great tires (have them on my FD), should work great for your usage. Better in wet/inundated conditions, but more $$$ and less hardcore for autoX.
Another option: Nitto NT05 (not much water-channeling capacity, though!)