SV is nice if you just want to show up, run, and go home whenever. Courses are quite a bit smaller, but is good for a casual introduction to autox.
Next SCCA one is 9/24 & 9/25, which are open for registration right now. There's a few mustangs that run at the SCCA ones regularly. If you just want to check it out (and not drive yet for whatever reason), Saturday is a good day to come out & get some ride alongs.
Saturdays are pre-reg only & usually sell out. Sunday you can pre-reg online or show up day of.