The pilot reported that he was departing a remote off-airport landing site in his tailwheel-equipped airplane. After assessing the physical site, which was sloped on both ends and the current weather conditions, he selected a takeoff direction and a takeoff abort point. During the departure roll, the airplane failed to accelerate past 40 knots, exited the departure area and impacted brush and trees. The airplane sustained substantial damage to both wings. The pilot reported no preaccident mechanical failures or malfunctions that would have precluded normal operations. In the recommendation section of the NTSB Accident/Incident Reporting Form 6120.1, the pilot listed several ways that the accident could have been prevented which included a more accurate assessment of the departure site, the establishment of a more prominent takeoff abort speed/point, or if he had been more proficient in aborted takeoffs.