On the Summer Solstice weekend the Audax Atlanta Randonneurs organizes a challenging 300K (186 miles ) round trip event for members on the combined SC/CL trails. To get credit for this ride it must be done in less than 20 hours including the three check point/rest stops. That's a minimum average of 9.3 miles per hour. On the June solstice (longest day of the year) the randonneurs try to finish the whole thing before sundown. Randonneurs from other states usually join in. It is not a race but everyone's elapsed time is recorded. Completers qualify for a unique cycling medal. They also do many other 200K/300K rides throughout the year. If you are interested see audaxatlanta.com and RUSA.com for details.
This is also a great weekend to ride the Whole Thing one way, rest overnight, and go back on Sunday. Or have someone take you by MV to the other end and then ride back in one day. Be sure to have all the stuff you need to repair a possible flat tire. If you have a breakdown on the Trail in the middle of NOwhere, there is no way for someone in a car to drive up the Trail to rescue you, right?