The combo of suggestions, including leaving the boot in the sun and tucking back the top as I bring it down did the trick. I was even able to (carefully and slowly) work the excess boot material into the gap behind the rear seat (make sure your nails are trimmed!). Thank you to all who offered advice.

Now this is resolved, I am interested in opinions about leaving the top down all summer versus putting it up nightly. My top man recommends the latter, but he isn't man-handling this boot every day. Can anyone talk to the risk of not putting the top up each night? Will it affect the life of the top?