You'll need a WAC because the VNC doesn't go down far enough but you won't need the Tassie maps.
The standard route from Moorabbin would take you near Leongatha and down via the western side of the Prom, past Deal etc as you have already suggested so you have that part right.
Let me know if you need a contact there for facilities etc. Pick some good weather and you're good to go!
Enjoy.