I'm not sure if its there or not after all the bad reveiws people gave it from TCCRA after they had a race there. Your best bet is to go to Village Creek. They have several miles of trails now from the TORN race that was there. Really fun lay out also. I bet its even closer to you than Thunder mountiain.
Check out VC's website.Generally the trails are always open no matter whats going on MX wise. We are in Mineral Wells and thats about it for trails. If you want close MX, Lucky's landing just opened back up at the I-20 and the brazos river south of Mineral Wells. We went this mornind and it has changed alot for the good since the last time it was open. Puts some G's on ya.