Very nice Rex, especially from Townsville - my recollection is that there is definite light pollution there, especially from the inner suburbs (where my wife's parents live). Out past Mt Louise i guess it would be darker. Still a great result, especially with an unmodded camera and the basic 75-300 zoom (which I also own but have never used for astro work) - you should be very happy
Just for comparison, I had a quick play with your image in PixInsight (hope you don't mind...) - I applied some noise reduction, removed the green colour cast and tweaked the colour and luminance curves and saturation.