Our old Bergmann (??) cultivator is made entirely of 1/2 by 2" flatbar and has served us well, even with 90hp in front of it pulling it to the frame. the flatbars to which the teeth are mounted are flat, and it has four longitudinal flatbars positioned upright over them. That means on a 3 meter working with they are about 2 feet apart.would 3by3 steel tubing be overkill for a 10-12 foot cultivator? what sizes steel should I use?