The commercial certificated pilot reported he was flying at a low altitude over rising terrain during a Title 14, CFR Part 91 business flight, searching for sites to deploy a tent camp in support of a lodge operation. While approaching a ridgeline, he stated that a powerful downdraft forced the airplane into a brush-covered hillside. The pilot reported that neither he or the sole passenger were injured, and that there were no preaccident mechanical problems with the airplane. The airplane received substantial damage to the wings and fuselage structure.