Placement of HOV Sticker in S Florida

I live in south Florida, and my dealer applied for and obtained an HOV sticker for me. The instructions tell me to place it on the bottom right of the rear windshield. For any car but the Prius, that seems like a no-brainer. But on my Prius, that means below the spoiler, in the area that looks like it belongs to the "trunk." Is this correct. And this means that it's exposed to the elements, as well as open to theft. Is this what Florida wants? My dealer doesn't know, and all previous postings seem to be from years ago. Any advice greatly appreciated.