The pilot had a six gallon fuel reserve in a container onboard the airplane in the event of an off-airport fuel stop. During the flight, he elected to make an off-airport landing due to low fuel. The pilot stated that 'The general terrain was rolling and at times mountainous.' During the precautionary landing, the pilot observed a narrow ditch and added power to overfly it. When the wheels touched down, the left main gear collapsed, and the airplane nosed over. Neither the NTSB nor the FAA were notified of the accident before the airplane was moved from the accident site.