Cessna 172 Pilot back taxiing to utilize full runway length at a non-towered airport at night must abandon the runway when a landing aircraft appears on short final.

Narrative

I taxied to a position just short of Runway 25 on the south side taxiway closest to the departure end of the runway; approximately 100 feet from it. I performed my before-takeoff check and engine run-up. Right after I finished the run-up; I heard a transmission from an aircraft reporting 4 miles out on the downwind for Runway 25. I thought it was an unusual report but I did acknowledge it on the CTAF/Unicom frequency and transmitted my intentions to back-taxi for departure to the beginning of the displaced threshold of Runway 25. I wanted to use the entire length of the available runway. I looked in the direction of the final approach to Runway 25; made sure it was clear and started to back-taxi. I had back-taxied a distance of less than 50 feet when I suddenly visually acquired the position lights of an aircraft on very-short final to Runway 25 that appeared out of nowhere. The aircraft in question had no other lights on. I immediately applied full power; veered to the right and exited the runway as fast as I could. Unfortunately; I could not avoid going onto a pile of rocks covering a flooded ditch next to the runway. The down-sloped ground was wet and soggy and braking action was less than optimal. The area was not lighted. After landing; the other aircraft taxied back to Runway 25 on the north parallel taxiway; the pilot briefly looked in our direction and immediately took off. I did not see a standard size tail number. My propeller did not strike the ground and my own close inspection of the blade tips did not show any damage. I also inspected the main and nose landing gear and did not see any damage. The nose wheel pant was seriously damaged. I understand this incident resulted in loss of separation between the two aircraft; one of which was mine; both horizontally and vertically. Depending on the point of view it can be considered a runway incursion or a display of poor traffic pattern and night time flying technique. This incident could have been prevented if the other aircraft would have flown a standard traffic pattern; had lighted anti-collision and landing lights and its pilot had correctly reported his position..