Now you're getting it Jester!
One point though, I don't think you understand just how isolated the north really is. Even in the more populated areas there's still vast stretches of beachfront without anyone around. There's no problem slipping ashore under cover of darkness, something the police can testify to in their struggle to intercept smugglers.
You go ashore up north and almost guarentee you're not going to survive. It only takes one mistake - the vehicle isn't where it's supposed to be, the landing was in the wrong spot, the weather is hotter than expected that day, and you're toast (litterally in some cases).
Dogger, I like what you've got there. Not sure I'd be nuking Brisbane in preference to Newcastle or Wollongong though (both MAJOR industrial centres).