That could work, they could cut a cannel to lake Erye (Sp?) and flood it giving OZ an inland sea.
I also think absorbing the tats from Maori culture would be cool and they should ride moa's and train the great eagles (the things that ate moas) how cool would that be.
Hmm...me likey. However, would an inland sea make the desert more hospitable to agriculture or less?
Maybe if they grow salt-resistant plants or turn the now-saline lake/sea into a giant fish- or shrimp-farm, that might work.
However, some writer made a good case that rice agriculture is economically conducive to free laborers and not slaves. Perhaps the creating an Australian inland sea to grow salt-resistant rice by the billions-of-tons could lead to serfdom or tenant farming in those regions while outright slavery is used for public-works projects and the like.
Heck, if the "Oceanic Draka" are smart, they might allow for some social mobility--if you're a good slave in the mines or canals, you get a rice plot for yourslf and your family. Gives the slaves incentive to work hard.
Having them ride moas and the like is getting a bit absurd*, but I can imagine them mixing with the Maori and the resulting culture being really scary-badass (complete with tattoos).
*At least as cavalry. Maybe having the president being pulled by moas on a chariot on ceremonial occasions is doable.