The pilot reported that during final approach to the 5,002-ft-long runway, the wind was reported as light and variable. Just prior to reaching the runway, he felt a gust of wind push the airplane from behind and to the left. The pilot corrected to the right and it took longer than normal for the airplane to touch down, but the pilot believed that he still had enough runway remaining to stop. Once the nosegear touched down, the pilot realized that only about one-quarter of the runway remained. He applied heavy braking and the airplane began to skid. The pilot realized that the airplane was going to travel off the end of the runway, which had obstacles and a drop-off, so he steered left, off the left side of the runway. Both main landing gear collapsed in soft, muddy ground and the airplane came to rest upright. Examination of the wreckage by a Federal Aviation Administration inspector revealed substantial damage to the right wing and fuselage.