Finally got the right fit on the back perch. Took some 3M double sided tape, a piece of 1/4" laminate, some sanding, paint, a little time and patience. Oh, and 2 short screws. The laminate keeps the bag from wrapping down over the seat. Cut the same size as bag and padded between pillion and laminate, 3M tape bottom of bag. I believe it will work for me.