If you weren't in Qld I'd say look at getting a 3 way, to run on gas as a stationary camp fridge. You could pick up one second hand for less than another battery and way less than solar panels.
We take our old Chescold for extended stays, and leave the Waeco in the car. So I can go off for a drive and the missus still have food, milk etc back in camp.
The 3 way will last 2 weeks on a 4.5kg gas bottle.
However they will only cool a max of 30 deg below ambient temp. so not so good in hotter areas.

