Voice of perverted experience:
Short version: Don't get caught if you think it might be refused classification. At best they just confiscate it, at worst they report you to the AFP.
Long version: I've personally seen the AFP try to stick it to some shotacon fans. Fortunately for them, the AFP failed to gather enough evidence, but not for want of trying.
I've had packages of my own opened an inspected. Thank tenticles, it was the vocaloid erotic cosplay with well placed leaks, and not the Choco pop up book.
The awesome freaks down at
Polyester told me back when mangarotica was still printing that when a H shipment is inspected, they lost half of it every time.
If you use tracked postage, and they decide to inspect they will check it faster... but still check.
Lastly if they think you are supplying to a minor (or heaven forbid, you lied when you clicked "i am over 18") and they find porn in a package, a lifetime on the sex offender registry is the very least of your worries. remember that a minor giving prons to a minor still counts as supplying under australian law. Yup, you CAN go to jail for loaning a mate your dirty books.
I used to order from places like mandrake where i could get a model kit or a figure added as well, but I've had that shit inspected now too. You have been warned.
Or ya know, take advantage of faku books n just download stuff. In the midst of all those goddamend buggers downloading game of thrones, even the high res version of these delicious porns aint gonna be noticeable in our flood of torrent traffic.