The pilot received weather information and filed an instrument flight rules (IFR) flight plan prior to departure. Approaching his destination which was surrounded by high terrain, the scattered cloud layer below him became broken. The sun was setting, so after seeing a break in the clouds and not being comfortable with what he observed, he requested the GPS-A, approach. He then maneuvered to intercept the inbound course at the initial approach fix (IAF). Before reaching the IAF, he saw a clear visual path to his destination. At the same time, the air traffic controller was waiting cancellation from another aircraft, and advised the pilot should expect a hold. The pilot advised visual meteorological conditions (VMC) existed, and he would continue visually. He then turned, descended, and crossed the final approach course inside of the final approach fix (FAF). The controller then received the other cancellation and cleared the pilot for the approach. The pilot acknowledged and continued his descent. The controller then asked him to cancel his IFR clearance with him, or on the ground. The pilot replied he was VFR and would cancel IFR. The pilot had the town in sight, and estimated there was a 2000 foot ceiling. It was significantly darker below the cloud layer. He switched to the Unicom frequency, keyed the microphone 5 times to activate the runway lights but, did not see them. He tried twice more without result and tried to dim the screen on the flight display, as the electronic image of the approach chart was creating glare on his windshield. He was deciding if he should climb into the overcast, try to circle the airport, or try the lights again, and thought his last heading, would keep him over lower terrain. However, the airplane drifted right of course. A passenger then observed trees. The pilot saw them and pulled up but, the airplane struck trees and terrain, and was substantially damaged. Radar data revealed he never became established on the approach, never was in position to land, and never got closer than one mile northeast of the airport before flying into rising terrain. No anomalies with airport lighting were discovered. Examination of the approach procedure revealed the GPS-A was not authorized for use at night. Visibility was below VFR minimums at 2 and 1/2 miles, in light snow and mist, and a 1,400 foot overcast ceiling existed which was below the published minimum descent altitude.