As others said. around 7 racks should be plenty. Each year I host a BBQ with 60 + folks and do 15-16 racks, bushel clams, 20+ lbs chicken, smoked kielbasi, wings, etc and 15 racks (mixed baby and pork) is sufficient for that crowd. 35 Ladies should be fine with 7 racks. (7 fit on the WSM)
Good Luck!