The pilot reported that, he planned to fly one circuit in the traffic pattern, and then land from the south. The landing approach was uneventful, and having reached midfield, he began to initiate the flare. A van then crossed the runway directly in front of the airplane, and the pilot decided to perform a go-around. Although the airplane began to slowly climb, it was not climbing at a rate sufficient to clear the approaching rising terrain, and within a few seconds they reached the end of the runway. The pilot attempted to perform a forced landing into a clearing about 1,000 ft beyond the end of the runway, and shortly after impacting the ground, the airplane caught fire and was destroyed. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane or engine that would have precluded normal operation. He stated that standard procedures called for retracting the flaps once a positive rate of climb had been established, however he did not do so because the climb performance was not sufficient. The airport owner reported that, due to rising terrain to the north of the 2,300 ft-long private turf airstrip, landing approaches from the south were recommended. The airstrip was 100 ft wide and bound by trees immediately to the left and right.