After a few google searches, I would recommend any noobs in Coz hire a DM. Not the guide on a cattle boat, but somebody bound to the buddy team.
The dive shops are happy to provide a private DM for hire, but they usually need to know a bit in advance. Especially if, for example, four people on a boat each want a private DM, they may not have 4 extra DM's hanging around, and need to arrange this in advance.