[paulk]

Sails I have seen this on have a reinforced patch in the center with a ring sewn to it. The retrieving line is tied to the ring, and there you are. Since there shouldn''t be too much strain on the line, (the halyards and sheets are released, and the sail is collapsing when the retriever line is used) the patch isn''t usually too big or heavy, and neither is the line. If the ring is equidistant from the corners of the sail, the head and clews should all end up at the edge of the hatchway at the same time. You might be able to experiment by simply using rip-stop tape to attach a temporary ring on the sail to see if it works for you.