Do not flights Perth/Melbourne go well south of the coast over the bight?
Passengers on these flights are not required to clear customs on arrival.
Passengers flying the QF flight from Melb (I think) to Melb via Antarctica without stopping do not even need to take a passport. I think that you have to actually land somewhere else. I could go check the AIP as I think that there may be something in there but maybe later.
FRQ CB