I have a family reunion to attend on the 18th and will be riding Montgomery Bell State Park (Dickson).
It's a bit of a drive but the MB (monkey bell) trails are excellent, well-marked trails with all levels of excitement. Jennifer rode with me out there last year. The shortest loop is ~4 miles and the race route is 20 or so.
START TIME 8 instead of 7, to allow more drive time.