I'm from Aus too ! I started really duck footed with +15/-15 and just tweaked it as I went.. I ended up with 2 boards. One has the previous settings and the other has +15/-9.
Look at all the Aussies on the forum atm , Im heading to perisher this weekend so look out LOL.
6'3" 105kg here, stance of 560mm centre to centre +18 -15.