Plenty of useful tips so far..
Just my 2 cents worth,
Its true there is now T coverage across most of the Nullabour now. A few towers on the highway, and more along the train line. Forrest, Rawlinna etc have towers. At altitude you can expect to be in range most of the trip. But just dont expect that at 500ft.
If you can, dont pressure yourself to arrive by a certain date.. The weather this time of year can be quite unpleasant. I have departed a station west of Forrest in clear sky for a 40nm ferry intending to do a survey flight, to find the block in low cloud and fog. By the time i returned to the station, the fog was rolling in there and i just got in. It stayed around for half a day.
Be prepared to try different altitudes to find a good ground speed. Remote area wind forecasts are not always perfect.
Have the details of all the strips along your route easily at hand and be prepared to land for fuel if you have any doubts about "getting there". Ceduna, Nullabour rd house, Forrest and Caiguna are about it. Just be aware that the dirt strips may be mud ones...
Spend a night at Forrest, the dinner is pricey, but good !. Breakfast pack too and a hangar for ya plane. Spent months out there, some of the best night skies !
And last light has been mentioned, allow plenty of time to arrive, much more than 10 min if you can. Fronts etc moving in from the west can see the sun disappear behind clouds much earlier than you think..
As well as all your nav gear and ipad etc, i keep an old cheap aa battery powered gps in my bag, just in case.. And spare batteries.. I felt much better flying the Tasman with it there, even though i never got it out...
And if you have 2 coms, 121.5 on one of them.. You never know.. If its good enough for the big planes, its good enough for me.
PI