My father and I modified a western harness to d riing. We have a team of suffolk cross 15.2 about 1300 lb. What we did was harnesss the horse. Then measure from the hame bolt to the belly band. We took 2 in. from that measurment. because of the large Dring. We used a framing square to get the all important 90 degree angle. lay it on the hame then measure along the line to the belly band. we have had no problems with the harness. The rest of the trace can be added to for your preferd length. Less barton video will help you set up your team.