An associate of the pilot/owner stated that he had departed at about 2030 CST to get some night practice prior to getting a day VFR restriction removed from his private license. Reportedly, the owner/pilot and an instructor (CFI) were intending to fly together and practice touch-and-go landings. There were no known witnesses to the accident. The aircraft was found about 4 hours after it had crashed. An exam of the crash site revealed the aircraft had collided with 70 ft trees near the approach end of runway 35. Impact occurred in a slight right bank and slight nose down attitude, as if the aircraft was on a base to final turn, but too close in and too low. No preimpact part failure or malfunction was found during the investigation. The CFI, who was acting as a safety pilot, received serious injuries and had no memory of what occurred during the flight. There were tall trees near the southern part of the runway which may have obscured the runway lights when viewed from the east or southeast.