Z visa for australian passport holder

I don't think you can get a visa from Thailand if you have no valid long term visa/permit there. Just try to apply in HK through the Commissioner's Office of China Foreign Ministry, it is easier for you.

The reason for asking the question that Hong Kong no longer offer this service so I am looking for an option other than going back to Australia

Hi, I said that because I have a friend with UK passport who was refused visa application there last month. So, you'd better contact the consular office for more information.

Thanks Daphne you answered my question

Yes, should be OK. The paperwork should state you are applying in Thailand though. As you are applying for a Z visa, it should be easier than applying for an L visa and thus you would not require any Thai work permit or long term visa. That requirement seems to be applied mostly to L visa applicants. Having said that, it may still be possible to apply for an L visa as a tourist with all the right documents but that is not relevant in your case.