The pilot stated after takeoff while en route to the destination airport he elected to fly to a private airstrip (Bates Field) located in rolling farmland. He lined up onto base leg for landing to the northwest on the upslope grass runway, and turned onto final approach. With 40 degrees of flaps extended he identified the intended touchdown point and flared but then climbed to attain the intended touchdown point. He landed, “but too hard and bounced up…” then touched down on the runway but drifted off the runway into 6 to 8 inch high grass. He added power to abort the landing but impacted a knoll at the top of a crest of a hill, then continued climbing. While safely airborne he assessed the condition of the airplane noting the pilot and co-pilot doors were ajar, but did not find any other damage. He flew over the private airstrip and did not observe any damage then elected to proceed to his destination airport, where he landed uneventfully. While taxiing after landing he noticed the left landing gear was out of position. He further stated there was no preimpact mechanical failure or malfunction that caused the hard landing. Inspection of the airplane by a Federal Aviation Administration inspector revealed damage and distortion to structural tubing in the cockpit, and wrinkles in the fabric adjacent to the left main landing gear.