The pilot of the tailwheel-equipped airplane reported that he was landing at a short, unimproved, off-airport landing site with a malfunctioning airspeed indicator. After touchdown, he immediately retracted the flaps when a strong gusting crosswind lifted the left wing, and the right main tire simultaneously impacted a large rock. The airplane bounced into the air, and he applied throttle to arrest the airplanes descent and touched down again. Realizing he was beyond the halfway point of the landing surface; he applied full throttle and initiated a go-around. The airplane failed to gain altitude, stalled, impacted the ground and nosed-over sustaining substantial damage to the left wing, vertical stabilizer and rudder. A postaccident examination revealed no anomalies with the airspeed indicator instrument; however, a blockage was present in the pitot/static system. The pilot stated that the accident may have been prevented if he had returned to his departure airstrip when he noticed the malfunctioning airspeed indicator rather than continuing and attempting to land at the short, unimproved, off-airport landing site.