Yes, a polite request is perfectly acceptable. You can provide a link that takes them back to the book's sales page at A-zon. I'm not sure if it helps, though.
The problem with that is that when the reader gets to the last page of the story, much of the back matter is missed when the reader is automatically taken to a form for the reader to fill out to provide a review. You can be sneaky and not put a page break before the back matter to avoid that.