The Australian working holiday permit this year is 24 months. Not sure if thats a recent extension. You are also permitted unlimited extensions to this provided you continue to meet the criteria (under 30 years of age etc). I figure if you are employed by a company for, say 12 months, it shouldn't be too difficult to approach your boss for sponsorship if you wish to stay longer. Please let me know if I'm missing something.
I'm only aiming for a light twin job, I'm sure the bigger players would prefer nationals on their flight line.