@Mark *******
message sent. You could start preping the documents now, but dont apply until you are back in Aust. You could qualify for workcation DTV. There is no minimum income requirement for this visa, but I believe it does help - you can write a letter as the sole trader regarding this using the templates i mentioned above.
As for the savings you will need 500,000 THB in a personal bank account - and ideally for 3 months, so transfer it now and apply soon.