Hi rhtrudder
I have been across east- west and back a few times and you may have to use avgas sometimes unless you have jerry cans and are prepared to walk. The nullabor is the easy bit. Coming west after Ceduna you get to Nullabor Roadhouse. Have a look at the whales this time of year at the head of the bight before you land. Taxi up to the roadhouse, avgas at the back or drag your plane right to the the bowsers for PULP, (no live props at the forecourts of any of the roadhouses.) Accom food and beer avail at all of the roadhouses.
Boarder village- avgas avail in shed at west end of strip, only about 50 mtrs to the pump if you have a jerry can.
Eucla- overfly, can't taxi up to the settlement.
Mundrabilla- fairly long taxi up to the roadhouse north of the strip. Stop motor and drag plane over cattle grid near Hwy(you won't get throu the gate if you have a low wing). then cross hwy to bowsers. No avgas here PULP at bowser.
Madura pass- overfly, can't taxi to the roadhouse.
Cocklebiddy- can taxi close to bowsers then drag in.
Caiguna- taxiway leads up to avgas bowser behind roadhouse. Only about 30 mtrs to bowsers if you have jerries.
Balladonia roadhouse- awkward taxi to bowsers. I usually drag it up to to the bowsers, much safer.
If you can make it to Serpentine from there you're in, or you could take a full jerry and stop at Newdegate and top up. You can also walk to the fuel station from the strip, about 1 klm. Alternatives are going north from Caiguna or Balladonia to Kalgoorlie or going south to esperance or Albany( not too good at this time of year). I usually make the straight run from Balladonia to the west coast without refuelling in my Savannah, comfort stops either at Newdegate or Katanning.
Hope this helps fill in the gaps, have a safe trip.
Cheers
Rick.