Here's a thought. It may not work but it might be something to check into anyway.

It's relatively easy for us to get to HNL at that time of the year. Have you checked to see if HA or AC has any specials from HNL to SYD? We also have pass agreements with both. If memory serves me well then AC tends to run full but Al could probably answer that better than I.

Not sure If I helped or just added to your confusion.

Good Luck!