I know of one Dash8 Capt who is CVD and holds a medical that says Australian airspace only. Suits his needs. Obviously Day/Night/IFR..
Talk to Arthur P as indicated above - he is the wiz! You will find him on the CASA DAME list in Geelong.
a) seek exemption (aka wise and proactive Dr)
Suggest you don't go down this path until you have spoken to AP and done all the required tests and know what the restrictions on your PPL are. If you ask the DAME to do a CPL medical that should place it all before you.