Problem will be our friends at Macquarie Bank, who get a veto over any 'major' airport development within 100km of YSSY. Thank Little Johnnie and his good mate Max Moore-Wilton (who happened to slink out of the PM's Department and into Macquarie Airports) for that little cracker. One might hope comments shooting down Bankstown are not being made with an eye to anyone's post-government gig...
Riccy would work, close to the putative catchment area, less issue with locals, a train station across the road, a good ILS-ed runway, no need to upgrade twys or any of the rest of the hardware, maybe just a bit of a tack-on to Air Movements (which has its own entrance anyway so no punters driving through the base proper). Indeed if it resulted in upgrades to local feeder roads and train services, the locals might actually support it.