The pilot had completed spraying operations for the day. He decided to proceed via a friend's property at Sprent to pick up some mail. There is an agricultural strip located on the property but it is some distance from the house. Instead of using that strip he decided to land in a paddock close to the house to save himself a walk. He had used this paddock previously and considered it suitable. The distance from fence to fence in the landing direction that the pilot chose was approximately 250 metres. The first 200 metres had a steep upslope and the last 50 metres was approximately level. Late in the final approach the pilot realised that the speed was high and that he had misjudged the approach. He forced the aircraft onto the ground some 95 metres beyond the approach end fence. The aircraft bounced and touched down again 40 metres further on. From this point heavy braking marks were evident. When the aircraft came to the top of the steep slope the pilot realised that he was not going to be able to stop before the fence at the end of the paddock. There was insufficient room to groundloop and the pilot decided against attempting a go-around as there was a power line beyond the end of the paddock. The aircraft ran through the fence at the end of the paddock, across a driveway and came to rest straddling a fence on the other side of the driveway. When the pilot vacated the aircraft he noted that there was a 10 knot tailwind. The pilot believed that he had a crosswind for landing but there was no windsock at the paddock. It was established that he had been spraying very small paddocks in hilly country, requiring a high degree of concentration. With the day's spraying operations over he had relaxed and did not give his full attention to flying an accurate approach and landing.