The race organization had a course description. The trail should be awesome, because it's at Quantico Marine Base and the US Marines maintain it! I should get there early enough to pre-ride the course. I have already registered, and if I get there 2 hours before the race start, I should be able to take one slow scouting lap. The race is 2 laps of 7.5 miles each lap.
I won't go hard riding today, just about 8 miles slow to the post office and back to ship a package. On road. Should be good enough to let my body not feel stale at the starting line, but shouldn't be hard enough to make be lethargic.
I have been drinking a lot in the past few days. Today I start with packing on carbs. Spaghetti dinner, mmmm. I will probably fill half my camelback with water and the other half gatorade or powerade for some extra energy. I have a tendancy to drink a lot from my camelback, so I will bring a water bottle to put on the frame.
Thanks for the advice guys, I'm now feeling better about this.