When I was living out there, I never had the opportunity to get to Buzzard Canyon. I always had something conflicting with their open wheel weekends.
However, I did make it to the coppermines ORV park a few times.
The coppermines are about 20 SW of Altus, it was a fun park with good people from all aound.
To get there from Lawton:
Head west on 62 to Altus,
Turn South on 283, travel for about 10miles
Turn west on E1750 (Elmer Rd), travel for about 10miles.
the coppermines are between N1950 and N1920.
However, google them as they don't always have Open Wheel weekends.