You posted this before and I had asked the details to see if I can tag along with you.
Stay camp here: mulberrygap.com
Ride the Pinhoti's right out of the camp site. Check this 28 mile ride. It was Mulberry -> P3 -> P4 -> Ft. Mountain and back. Over 5,000ft of climbing. http://connect.garmin.com/activity/9639565
Take your bear spray! On the way back from Ft. Mountain, I tried to ride up the "noname trail" back to P4 only to be forced to walk for over 3 miles since it was too steep for my tired legs.
For an easier ride on mostly dirt roads, do the Mulberry Gap -> Shakerag Rd -> Colhutta overlook -> Bear Creek -> P1 -> P2 and back. Still plenty of good climbing over 3,300ft. http://connect.garmin.com/activity/9639546
Either ride will take 3-4 hrs if you stop a lot like I do to take pictures and soak in the scenary. But you can shorten that or add more milage by adding tons of more Single Track or Road...
All within 8 hrs drive.