Since this is outdoors we most likely will have around 10', most people doing outdoors events give 10'x10' spaces because that gives you the ability to set up a standard awning to protect from sun and rain.
Talking about tables, I have Scott's (Lilrat) 6" table that needs to get back that direction that I bet he would not mind us using, and a 30" round 42" tall table that works nice for sign-ups and raffle tickets that we can use.