<<It may be possible for an aircraft to be owned by an overseas based entity (with a Australian listed as operator). In which case the company does not pay GST in the first place (think Singapore, Delaware (USA) or maybe Malaysia). You will pay GST if that company has such a tax.>>
Interesting, so if you bring in an N-reg, which has to be owned by a US individual or a US company (probably registered in Delaware), and it stays on the N-reg then you may not have to pay Australian GST?