Hello, please take many responses here as just opinions though some may be correct yet some others are not good advise.
If you attempt to 'run' your biz in VN without properly establishing yourself legally to do said in VN then you are asking for problems. It's illegal to do business in VN in your own name without a legal status and proper taxation/filings. [BTW: It is possible to have a VN corporation w/o a VN partner but it takes a few months, more docs and it involves $20K USD minimum investment in VN.]
If you 'hope' that you will be OK remember the ole saw...'Hope' is a four letter word.
Let me clarify an example but I think you already get it.  Employing a local VN to clean your house, tend your children, manage your garden, be your personal assitant, be your girlfriend...? No problem! no issues! and you can do so with any valid visa [BTW I know of no 1 year tourist visa, so we really taking about a biz visa].
Now let me say up front, if you can operate your 'aussie biz' and NOT hire any locals then you are fine to do whatever you want and the VN have no complaint.
But the moment you start doing business in VN and employing VN or other persons [watch out employing foreigners living in VN on tourist visa, they are not supposed to work] for the purpose of making a profit 'anywhere' then you are doing business in VN and I can't imagine the VN believing you if you try to explain you're NOT doing business in VN. The VN get really, really up your backside when they find or suspect a foreigner is doing business directly in VN without proper corporate/business status. WHY? Because they know they are about to get a big pay day! BIG PAYDAY that the VN immigration system lives for!
What happens? Sooner or later you will get a visit from the immigration police [and / or local police] as all it takes is a local VN or legal foreigner ratting you out and then you will have a problem. If you are operating your 'aussie biz' or employ VN workers in a foreign biz on an tourist visa then you are open to a 40.000.000 VND [2,000 usd approximate but the amount may differ from officer to officer ..city to city] fine, plus possible deportation, and you can expect to pay 20.000.000 VND $1,000 USD of that fine [why 50%, so that they can shake you down for more under the table, read on... if you paid the full amount then they would have to do an official thingy and maybe deport you...if they just shake you down then they know they can come back later is see if you are still operating and shake you down again....] PLUS you will have your passport/visa seized in the process and regardless of paying your 'fine' above you will get shaken down for another 20.000.000 VND [1,000 usd approximate] 'secret fee' to enable the returning of your passport/visa OR they will deport you so you don't have much choice as you broke the law.  Note that there will be other fees and you will have to locate an intermediary to negotiate and deliver your 'secret fee' as the police will not do the transaction with you to protect themselves from bribery stings/complaint.  Lastly, IF you get deported you will now have a red stamp on your passport and you will be in the system as deported and your VN dream is over...done...toast. Even after you pay the fine to avoid deportation you will now have an open file 'suspected of doing business illegally in VN' with the immigration and secret police. That file will probably never get closed and you stand the chance of periodically being hunted down and interrogated again by the same folks as they want to see if they can extract another bribe for your infraction and lack of compliance if you were so gullible to beleive that your 'fine' was paid and now they would look the other way.
In short you better just do it right and get and stay legal.
Anyone who says what I have submitted above is bunk does not know anything and don't listen to anyone who tells you that you can do what you are saying you want to do w/o proper legal/biz status.
If you want/need a legit legal biz VN associate/partner so that you can do your VN corporation etc. you can try contact firms that offer said servcies....if you want to contact me, then feel free to PM me and I may be able to refer you to a legitimate source.