I've just found out that there's going to be a race in Freetown State Forest this September. The Freetown 50. It'll be held on September 15 and registration starts August 15.
It's a 25 mile course with a mix of technical singletrack, dirt roads, and a bit of pavement. There are 3 different ways to register. You can race the full 50 miles solo, or do a 2 person relay with each racing 1 lap, or opt for a 1 lap 25 mile race.
I've ridden the course and its a lot of fun. They've selected some of the best singletracks out there and connected them with fire roads. The singletracks are technical and beat you down, so the fire road sections are welcome.