Dunkels is in an industrial area....plenty of parking lots. I went one year, got there late at night prior to the Sunday meet and was able to cruise through the whole shebang with the security guards blessing. We were pretty lubricated and the headache the next day was met with LOT's of sympathy.....
I would bet that you could park onsite and crash/sleep there.
http://www.nosubstitute.org/events/Dunkels...b01/default.aspHere are some pics....click on the "Dingle" icon on the bottom left and see the secret pics of our nocturnal jaunt thru the museum.....