its fine, as long as you can prove your stay, funds and outbound ticket, having gaps in going to thailand is fine, its more so if those gaps are 2days in vietnam every couple months is what will raise suspicion.
if where youre staying asks for a copy of your passport, or asks for a photo of the page, they are most likely doing your tm.30. every hotel i stayed in and even some "selfcheck in" accommodation asked, and sent me a confirmation of tm.30 lodgement. some have not. so it seemed to be the difference.
im a tax resident too at the moment in Australia, but if i move to thailand full time(or more than 6months a year), i am not returning to Australia to live (only to visit), thus i will have established social and economic ties with thailand, the test comes up with foreign resident for this.
interesting, do you stay in australia for more than 6 months? then you are a tax resident. Do you have social or economic ties to another country? this includes moving overseas and opening a bank account and setting up financially in Thailand too