Hey James, regarding your PPR and Granny flat idea, you might want to have a read of this if you haven't already.
http://www.bantacs.com.au/QandA/index.php?xq=435
Here's the thread: http://somersoft.com/forums/showthread.php?p=1109375
I'm interested in understanding how 4 properties could derive so much rent.
I'm assuming all the rent is above board. None of this rent to multiple unrelated parties on the same site stuff.