The pilot reported that while in cruise flight, he noticed that the engine temperature had risen above the normal operating range, and he felt that the engine was developing less power. He elected to make a precautionary landing on a flat grassy area. The crosswind was stronger and gustier than he expected and the airplane encountered a gust at touchdown, which placed the airplane off center of the touchdown point. He added power to go-around, however, he was unable to establish a climb as the airplane became unstable in the sand and bushes. The airplane subsequently nosed over, which resulted in substantial damage to the wings. Other than the elevated engine temperature, the pilot noted no other mechanical malfunctions or failures with the engine that would have precluded normal operation.