Scott, welcome! The SoCal Hummer Owners/Offroaders Group is actually quite active. Check out this link for the "local" forum:
http://h2club.org/6/ubb.x?a=frm&s=8296099471&f=8756030324
Obviously that forum is nowhere near as active as this one; but you can get notices of upcoming local events like the 2N17X run this Saturday and "Slitherfest" in September.
Hope to see you in the trails soon!
