It's one hell of a drive Bitters.
But sounds great.
Back when swine flu hit, I loaded up my young family and drove from Melbourne to Port Douglas. Stopped at every Maccas on the way . Took about 2 weeks. The highlight for my 4 year old son was a dead pig on the side of the road not far from Townsville. Oh the memories. Don't know how many times I pointed out the sugercane.
You could swing through Broken Hill. Though not sure what it has to offer and not sure if you need a 4wd. Then sun yourself later on in Mildura.
Personally I think outback SA has more to see especially Cooper Pedy.