I know very well that we do not have yet the scale of large, but our first convention in the name of GénérationS Playmo took place the wee-end of April the 21 and 22 in Savoie (France). We accomodated surroundings 800 people. Here some Photographs of gathering. For more I see some advise you to come on the Playmofrance forum.
I am really sorry to be able to put of it to you safer if you wish it. Will know that it have the medieval one there, western, and full with other.