That's an interesting question, mate.
IMHO, ..Tyre pressure, is the most important thing on sand. One of the problems I have found is that you cannot always predict exactly where the soft and really sold sand starts and finishes.
I ran 12psi front, 15psi rear, and 12psi on the Camper Trailer, all hot pressures, in the Canning, in 2009
Total weight was 4.7 tonne. It was like a boat for the first 10 minutes every day.
Now the tricky bit !
I soon found out that driving high 1st or 2nd gear, was too fast, and that if I continued, I would damage things. That was after the first dune, but out there, you get a chance to try a few things, as from memory, there is bugger all bigger dunes, till after Durban Springs.
Low range 2nd gear was heaps easier on the Mighty Poootrol.
At those tyre pressures, and the easy revving of the motor.
Another thing I discovered was you could feel the tyres lift out of the sand, and just cruise over the dunes at 1,800-to--2,000 revs, and do it relatively easy, even coming back down from Bililuna, in September in 45c plus heat, in extremely powdery sand.
In the Simpson, its slightly different, as the dunes are much bigger, but the same principal applies
Hope this helps
Cheers Buxter