Technically you would require work permit or visa and iam not one for breaking laws of other countries but in your case I would just apply for retirement visa and not inform or tell anyone what your doing what the authorities don't know don't hurt them not doing anything wrong by looking at a laptop everyday but like thai girls say upto you same same but different Chohk di
If your return flight is for a 35 day stay just get extension for 1900baht per person at thia immigration to cover your 5 day overstay but wouldn't advise and overstay stamp avoid that at all cost you may get away with out any issue but it all depends on the IO infront of you on the day remember it's thailand and there is never any guarantee of entry even with a clean record enjoy Chokh di
If you didn't know its thailand you are talking about nothing happens quick in the land of smiles and when we think the thai authorities use a lot of thought process to make decisions well think again because there is none guaranteed if you wish in one hand and urinate in the other you will get a wet hand first
your answer is true not sure where some others get their information from but there has never been guaranteed entry to Thailand even with visa or without entry to the Kingdom is upto the discretion of the IO infront of you on the day of entry they never need a valid reason to deny entry to anyone
yes but must remember if her entries to Thailand are very close she maybe asked question because if they the IO believes you are trying to stay in the country long term and not be a tourist than she maybe denied entry just because there is no regulation or rules for entry by air does not guarantee you entry maybe for her she should get correct visa as some comments have suggested it is just respectful to not abuse other countries standards Chokh di
You can only do 2 land border entry per year but no rule for entry by air if does another visa run by land probably will be denied and sent home must remember every time you enter thailand it is up to the IO infront of you on the day if he or she is kind and let's you in
If you have Australian passport you don't get visa on arrival you receive 30 days visa exempt stamp which is zero visa just a stamp in you can get one 30 day extension whilst in the Kingdom for 1900 baht or get 60 day tourist visa issued in Australia and than 30 day extension give you 90 days or border crossing by land get another 30 day exempt entry but you are only allowed 2 land entries per year but there is no set regulation or law for the number of times one can visit the kingdom by air but any entry to Thailand is at the decresion of the IO infront of you at time of entry whether it be you first time or your 20th time it is looked at as if you are a tourist or you are trying to live there without the correct visa get correct visa for your purpose and you will have minimal issues Chokh di