It would be really tempting to just grab a book, consume space in line, wait for her to take it, and then say “Nope, .... changed my mind. Besides, at this point, What Difference Does It Make?”
And leave her with the book in hand and a dumb look on her face.
How hard would it be to bring another similar-sized book into the venue, swap out the cover in the book section so it looks like you’ve purchased Hillary’s book, and then get her to sign it. Maybe Monica Lewinsky’s book was similar enough that you could just change the covers? LOL.