From: Cammeraygal Country
If you build your convoys in the ratio of 3 Liberties, to 1 long ranged tanker, (so 6/2, 15/5, 27:9, whatever), the liberties can refuel the tankers + a couple of escorts and go all the way LAX -> to Sydney by the left arm route, and back, without refueling down south. I also include about 1 tanker full of crude oil per month to keep the refineries going. That is all more efficient than shipping off map to Capetown and then up to Perth or Adelaide, but as time goes on you have spare capacity to do that as well anyway.
Apart from that Christmas island (PO) and Suva are good hubs to distribute from, but I'd suggest using the 16 & 18 knt AOs closer to the battle area. They also give you some flexibility if you suddenly need some underway replenishment.
"You may find that having is not so nearly pleasing a thing as wanting. It is not logical, but it is often true."
- Cdr Spock