The builders manual gives instructions for cutting this part with a radial arm saw. The princpal is sound but I dont have one and couldnt see buying one since I already have a compound sliding miter saw. I choose to modify the direction so that this could be done on a table saw - note difficult.
First scuff board as directed , then cut both ends per the call out. Since the table saw will be cutting through the scuff board unlike the radial arm saw approach the ends have to be cut first . After the ends ( top and bottom angles ) where cut to finished dimention , I moved the spar off scuff centerline and bolted it down per the instructions - ripped one side. Then the other - Finished.