The "Wilsons Prom" airport as you put it is actually a firefighting strip belonging to the Dept of Sustainability and Environment so not a place for a private aircraft unless in an emergency. It's closer to Yannakie than anywhere else from memory. That being said a mate landed there the other day for some relief of the urinary kind and nobody raced into tell him off.
"Casey Field" as you have mentioned was actually in Berwick and was closed to build the Monash University Berwick Campus.
These two strips are approximately 75 miles apart!