There have been lots of silly domestic decisions, the next national cabinet needs to force a national policy to be agreed and publised. 1 case in any state should not lock out a whole state.
Right now you can reduce risk by flying direct to destination, driving via other states and territories to get to your destination adds risk of having to navigate more jurisdictions. It might be against AFF norm of maximisng points, but i try to avoid unecessary transfers/connections and fly direct wherever possible and definitely wouldnt consider otherwise now.
WA , Qld, Tas and NT have form in changing rules with no notice whilst people are in the air, way too risky to contemplate travelling there anytime soon until transparent rules are published. At least NSW and ACT gave 2 day notice of Vic border closure, so no one landed from a domestic flight from Vic to find they had to turn around and go home or into hotel qurantine because the rules changed while they were in the air.
If you want to go caravaning, in 2020 its safest to stay within your own state, so you can always get both your self and vehicels home.