Just because we have 'x' amount of states does not mean we require 'y' amount of air frames, You need to base it off of the states likely hood to experience bush fires and the fire fighting services are generally able to predict with some degree of accuracy which area's are in more danger then others.
By rule of thumb Southern Australia generally suffers bush fires from December through to March (4 months) with Victoria and Southern WA experiencing the brunt of them while Northern Australia generally experiences them between April through to September (6 months).
So you wont be required to have all aircraft dispersed across Australia at all times, As it is the C-27J's loaded still have a decent range meaning you can having several located in a single state (ie: Victoria) that could then support surrounding regions (From Vic you could easily cover Tasmania, Southern NSW and Eastern SA) with a 10 ton payload.
A half dozen located in WA and VIC in December-March and similar numbers located in WA and Queensland/NSW in April-September would be more then capable of providing the needed support, If not then why not also acquire the MAFFS? They are easy bolt on bolt off kits for the C-130's that are in use by several nations.
"fire fighting services are generally able to predict with some degree of accuracy which area's are in more danger then others".
You're not serious are you? They can predict with some degree of accuracy?
The only thing that is 'predictable' about the Australian fire season is the 'unpredictability' of where the fires are going to occur.
How do you predict the possibility of lightning strikes that start many fires? How do you predict the idiots that start fires in the worst of conditions? How???
Have you been involved in unpredictable fires? I have, and it's not pleasant to say the least.
Many years ago I lived in a very leafy area of North/West Sydney, and out of the blue we had a very hot dry Westerly wind come up, some idiot started a fire on the Western side of the bushland and all the houses on the Eastern side of the bush (where my house was) were threatened, fortunately the fire front was stopped short, but you should have seen all the burning embers in the air.
My ex Sister-in-Law had a house in Canberra when they had their devastating fires, one minute they were told the fire front was many many hours away, then within half an hour they were told 'get the hell out!', they managed to gab a few boxes of possessions, they got out with their lives, but lost everything, and I mean everything (have you picked through the ashen remains of a relatives house? I have, not very nice).
My ex In-Laws went through the threat a number times when they lived in the Blue Mountains west of Sydney.
Three years ago I was on holidays in Victoria and drove the 'Great Ocean Road', three years ago it was wet as when we drove it, so what happened there in the last few weeks?
Two years ago I was on holidays in Tasmania when the fire season was on, and when we drove from Hobart to Port Arthur there had just been a major fire, we drove through all the little towns that had been burnt out.
Those are things that you just don't forget! Predictable? NO! Unpredictable? YES? And that's just my personal experience.
Have a look at all the assets, fixed and rotary that are currently deployed around the country:
NAFC Web Site
There are more than 120 assets deployed around the country by the various States and Territories, and it is their responsibility to do so, again, we live in a federation, we have States and Territories that run their own show, it's not the Commonwealths primary responsibility.
It's up to the various States and Territories to decide how much resources and where those resources are deployed, some fire seasons, the threat will be low, some it will be high, I really don't think its a good idea for the ADF and RAAF to become involved at a 'primary' level, not one little bit.
But again, it's not to say that the ADF and RAAF can't provide support or an 'emergency' or surge capability, of course it can, but it just doesn't have the assets to be able to be 'everywhere' and 'all the time' it just doesn't.
Bottom line, fire season is anything but predictable, its completely unpredictable!