I have seen a number of large Cubs used as tow planes. All worked best with the tow line attached at the top of the fuse right at the trailing edge of the wing. An A frame (an A shaped wire was mounted on the Stab with the lower ends of the A at the tips of the stab and the peak of the A at the top of the rudder to keep the tow line from wrecking thefin/rudder structure. This allowed the tow line to ride up over the rudder if things got cockeyed during the tow.