We have had more time to think about it and 3 months it is! We will be concentrating on the Kimberley's via parts of the Red Centre and Kakadu Litchfield that we missed last year.
I'm in real estate and work on commission only so 6 months is a long time for me to get zero income and not be seen around. And selling my own property doesn't sit well with me - I see too often how much they grow over time!
Also, after doing a budget, going for 6 months will cost us 4 times as much as going for 3 months (doesn't make sense but the numbers don't lie!!)
Anyway we have set a date for our departure - 12 months today - 6th April, 2012 (the day school holidays start in SA after first term).
Thank you all for your input and now the countdown and planning begins.