It's patrolled 24/7, there are also dogs on site (not the human kind).
You could theoretically get in and sneak around but it would be touch n go and you would have to aproach the site at night without torches on and then get over the perimeter fence unseen (hard).
Good luck, call me soft but I'm just gonna wait till it opens so I can take my kids the easy way.
Blakjak of the Sydney branch of the Cave Clan.