It could still be possible to make final arrangements like hotels and air tickets. It will be fun to put on their costumes but then its not necessary there are many shops close to the venue selling it and its inexpensive for most of the items. Most of the tents are fully booked by now especially by corporations for their staff or customers but its alright as bookings tent to start early evenings and so can sit in tent until they ask you to leave. So night time is actually fully booked. Do go tent hopping as you may be able to find a space.
Had a really wonderful time there and take note that lots of beer served there is only available during this period, after the festival its no where to be found.