The airline transport pilot, who was also a flight instructor, stated that the accident flight, with a commercial pilot in the right seat receiving flight instruction, was a personal flight with one passenger aboard. While en route to the destination airport, the pilot attempted to fly over a line of convective weather. While at flight level (FL) 410 and at 0.75 Mach, the airplane encountered “heavy” turbulence and hail. The pilot descended to FL 350 and slowed the airplane to 0.68 Mach, then flew about 495 nautical miles and landed at the planned destination airport, rather than performing an immediate landing at the nearest suitable airport. The airplane sustained substantial damage to both wings, empennage, and windshield. The pilot stated that the accident could have been prevented by having diverted about 80 to 100 miles north of the weather. The pilot stated there was no mechanical malfunction/failure of the airplane that that would have precluded normal airplane operation. About three months after the accident, the damaged airplane was discovered after an anonymous complaint was made of an unreported airplane accident. The airplane was located at the airplane owner’s hangar at the destination airport where it was undergoing repairs. The airplane make and model was not certified for single pilot operations and required two pilots. The commercial pilot did not hold a type rating for the airplane make and model nor met regulatory requirements to act as second-in-command for the flight.