All of this is spelled out clearly in the "DETAILS/REGISTRATION" link in the 1st post. Sorry you wasted your gas.

"In addition, the access gate will only be manned for a limited time -- please arrive no later than 9:00 and plan on staying for the day."

"Airport officials require us to submit a list of attendees in advance, so online regsitration is mandatory. Registration will close 4 May. ALL PARTICPANTS, INCLUDING ENTRANTS, CREW, AND SPECTATORS MUST PRE-REGISTER PRIOR TO 4 MAY TO GAIN ACCESS TO THE SITE!"