You posted this question in '09 and no one has been able to help you? I am shocked. Georgia Bonesteel has made a career out of this very operation!
If I understand the situation, you would stitch as much of the back as you can then finger press the last seam and slip stitch it closed. Invisible stitching, like closing up a teddy bear.
Perhaps Georgia Bonesteel has a video on this. Good luck, please send a picture when you finish it.
Butterscotch