You can get 20 miles one way on single & two-track by doing this apparent rerouting of Pinhoti 6-5-4 by adding P3. Start from the obvious new parking lot on Dennis Mill Road (about 1 mile north of Hwy 282/76, nearer to Chatsworth than Ellijay). As an out-and-back this makes for what Earthdog calls a "Fat Forty", a real endurance ride with a lot of rolling climbing, multiple creek crossings, fast two-track downhill and some gravel road. We did it on singlespeed, and I wished for more than a 19 tooth in back. The initial climb of ¾ mile is seriously stout, and it seems about 60/40 climbing/descending starting from this direction. While the "new" singletrack seems limited to about 3 miles, thereupon connecting the old two-track, it is a pleasant and challenging endeavor.
It is significantly more uphill starting at the Dennis Mill Road parking trailhead, that 60/40 split since you basically will climb all the way to 52 near Ft. Mountain State Park, before hitting P3 downhill. So you'll really like starting there when you're on the way back. We did the ride in perfect weather on Saturday, April 26, 2014.