CT Stickers for displaying in your van window

Another thread about badges for CT members at the NEC Show got me thinking - how do you know if you're pitched next to a regular CT contributor ?

How about CC producing a sticker for CT members to display in their vans ?

As an initial trial, how about the CC graphic design team producing an A4/A5 page which could be downloaded as a PDF document by anyone who is interested.  They could then fill in their CT ID and then display it prominently in their van window ?

What are your thoughts ?

Of course, the sticker would need to be easily removable, just in case you spotted someone else on site who you wanted to avoid !!