Finally....Vindication! You are the first guy to actually post up and confirm my diagnosis (what seems like all those years ago). Thank you.
Your tank will expand, no way around it. What you can do, and I highly recommend it, is purchase Moto's rear tank brackets. It took me a while to convince him to make them but they are definitley worth every penny. These will make lifting and returning your tank to the lowered position so much easier.
John