Getting married on a visitor visa but...

mawin

Hi guys, Hoping someone could read this and I would really appreciate your help by answering my question below or give me some links with topics similar to my case.

My girlfriend went to Sydney last April 2016 with a permanent resident visa. I, on n the other hand, lodged my tourist visa application. Hoping for the immigration to grant my request soon, we are thinking if we could marry in civil once I get there so we could process my fiance/spouse visa right after. Given it is possible to get married, I am still planning to go back to my home country up until my fiance/spouse visa is granted, and then we'll settle in Sydney for good. I wonder if it is possible to wed and if we are not violating any laws given our intentions and visas on hand?

Thank you very much in advance!