What about theft? Losing your bike or some essential component would end your trip.
Australia is a relatively rich and, mostly, law abiding country. Touring bikes are relatively rare and people tend to stare in curiosity, or amazement, rather than with thoughts of knocking your bike off. People tend to respect others property.
In any case who wants a second hand bike, without a motor, out there. Or panniers filled with clothes that haven’t been washed in a couple of weeks.
Generally just normal, common sense, precautions are required. It’s rather hard to steal a heavily overloaded bike and its attendant somewhat scruffy gear. Most of the public would find it hard to work out how to remove a pannier or handlebar bag.
In civilisation leave your bike in a public place, visible to everyone. Outside the supermarket, post office, etc where any interference can be seen. Where people are wandering around.
Opportunistic grabbing something is much more likely than losing the whole bike. Kids just mucking around being kids is the bigger issue. Reducing the possibility of snatching components like your bike computer or pump is a good idea, ie, hide those. Take your most important things in your handlebar bag.
Investment in a bullet proof combination lock at least gives you some peace of mind.