The pilot reported that he was conducting a high density altitude takeoff in the single-engine helicopter in gusting wind conditions. He reported that while accelerating to best rate of climb speed, the main rotor low rpm horn sounded at 97 percent, and he unsuccessfully attempted to increase the main rotor rpm back to 102 percent. The pilot aborted the takeoff and sought a landing site near the departure end of the runway; the helicopter subsequently touched down at a high rate of descent in a gravel parking lot adjacent to the airport and rolled over. The helicopter sustained substantial damage to the tail boom assembly and main rotor blades. The pilot reported that the helicopter takeoff weight was 66 pounds below gross takeoff weight. He also reported that the accident could have been prevented by shipping all personal items not required for flight to the next low altitude airport along his route of flight. A successful takeoff should have been possible at the reported takeoff weight. The pilot reported no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation.