Definitely call ahead for fuel, YAYE are going through upgrades at the moment so fuel has been off line for a couple of days here and there although that should be done by December. Coober Pedy had a few problems with the bowser during the warmer months last year too. Oodnadatta are not currently selling Avgas after the passing of Adam Plate from the Roadhouse, the Progress Assoc will get around to taking it over at some stage. Cadney Homestead's fuel supplies are also intermittent and will cost you an arm and a leg but nice to have the option up your sleeve.
It is hot out here already, 43 deg yesterday, whatever you're not carying in fuel, carry in water! Enjoy!