My boarding ladder consists of 2 lengths of stout Iine and a board with holes drilled in each end. The lines are knotted and passed thru the holes on one end, and then passed thru the holes in the aluminum extrusion that runs around the edge of the deck. I deploy it at the aft corner of the cockpit. I can reach up and grab it from the water. The board floats and you have to push it down and insert your foot between the board and hull. It can be removed easily, requires no drilling. The backstay interferes with using a transom mounted ladder on a M17. No Cost? Nothing. Boarding ladder and motor mount hanging off the back of that lovely transom? I don't think so. Whatever boarding device you decide on be sure to practice with it repeatedly, especially when tired. You may need to get back aboard was someday when your life depends on it. It can be seen in this photo in the stowed position.
