I just saw the question about cotton paper. I did a business card on Crane Lettra 110# and another on Reich 236# with that same PMS 812. They are actually a lot brighter in person.
http://bunnybearpress.com/portfolio/businessandcallingcards/bunny-bear-press-qr-code-cards/
If you want to go fluorescent I would recommend a whiter paper to get the brightest look.