I need to know the answer to this as well. I would have never thought that you would need to pre-register for spectators, so luckily I saw that on the FF2015 webpage before I made the 2.5 hour trip. I just finished making arrangements to bring a group from my church up tomorrow but am now hanging in limbo.
Please somebody tell me that spectator registration is still open.
I forgot to get my spectator pass ahead of time. They were still available today for $9 at the registration table.