I just did it recently (early Nov) and we took 4 days and it was perfect. I would very confidently do it on my own. From Vic we stopped at Balladonia (no reception from here till we got over the nullabor), then Ceduna and then Murray Bridge. We booked everything online through wotif except for Balladonia and the accom cost the most there @ $130/night. We got to all towns before sunset.

Things to remember, check tires, oil & water at least once a day if not more. Don't stop for anyone. And try not to advertise you are traveling on your own. Try and leave at day break no matter where you are, check sunrise/sunset before you leave (or on your phone when you have reception). Keep a very close eye on your speed in SA as they make their money from Ceduna to Adelaide and their tickets are some of the most exxy in Aus.

I did it in a little corolla with another girlfriend and everyone told us we couldn't do it, or that it was too risky and TBH it was easy. I have done it a few times before though. And I would happily do it on my own with kids, provided it was 3 days.