Can you get in touch with the AQHA and find out if they have clubs in your area? A lot of breed organizations have local chapters and clubs, and even if they don't just focus on trail riding, it may be one of the activities they offer.
Are you specifically looking for Quarter Horse riders, or just non-gaited/stock horse type breeds to ride with? There are all kinds of "trail riding" clubs around, but some clubs are more into socializing in camp than actually being in the saddle.
"Parelli horsemanship is just like painting by the numbers. You need absolutely no skill. You just put this color here and this color there, and when you're done, you have ... a mess no one wants." mp