I don't have an answer for this so I thought I'd start the discussion/thread.
I've seen lots of signage meant for "normal" stores; tape on the floor, printed round thingies that promote social distancing, etc. However, I've yet to find something ready made, though my search is by no means extensive, that might be appropriate for an art fair booth short of making my own. I've even "googled" images thinking I'd make my own poster to put up.
Anyone hit on something that they would like to share?