Salary sacrificing ...: tax
Sure there are legal ways to minimise tax etc and most of us do it but all else in reality goes out the window sooner or later.
You can claim and/or say what you want to the ato and csa but at the end of the day they both have ways of dealing with it and one of them for the csa is potential income.
Some may get arround things for a while maybe even for a long while but if it is not legal or it is a "loop hole" expect at some stage to be stopped, even penalised.
Get a good accountant even a solicitor but generally the bottom line is if you earnt it, it is income (simplified of course)
Years in business has taught me one thing and that is you can't cheat and expect to get away with it.
I have also found that it is far easier to get a fair deal by co-operating with the ato and csa and a fair deal at the end of the day is all you should expect.