I am a health care worker and amateur prepper, so I'll share some of my thoughts. At this stage the restriction is only travelling interstate. Social distancing is easier out of the city and the fishing is better but there are a few down sides I can think about.
If you do go, some of the things to think about are
How is your health? Are you in a high risk group due to medical issues or age? Medical resources thin out rapidly when you get out of Metro Adelaide. While community transmission of Covid is low in SA, things are changing rapidly day to day and week to week. Also as the outbreak continues, local country hospitals will rapidly be overwhelmed and may not be able to assist you.
Have you got any contacts in the West Coast that you could stay with or could help you if things get bad?
Do you have any family or friends that need assistance back in Adelaide. If you were stuck somewhere are unable to get back to Adelaide, would this be an issue.
I see you are reasonably self sufficient already. How much food, water and fuel do you carry and how far could you travel if suddenly things were locked down or if fuel supplies got interrupted? Would you be able to get back to Adelaide if fuel was short?
How good is your phone and internet network? I had trouble calling my parents today on the mobile network. They are in Melbourne and I got a prerecorded message from telstra saying that the network was having issues. Have you got any other means of communication is mobile communication and internet go down?
Likely hood of full lockdown is low at the moment but this is what you want to be keeping an eye on
The AHPPC advise the government on public health measures. They have already spelt out their trigger for full lockdown and this will be the thing to watch
Or maybe I am overthinking this and we should all go fishing...