And even the Thai Elite Visa, which is based on tourism does not allow you to work inside Thailand.
You need a Visa that allows you to work and a Work Permit to work inside Thailand.
Bite the bullit and become legit or keep on playing games with Immigration and keep asking if you are allowed back into the country to take care your left behind belongings.
Yes, the law from 1979 is still in place but differenty enforced for people residing long term at one address. Check with your local Immigation Office on how lenient they are with enforcement.
Copy all this answers, save the link on your phone, make sure your powerbank is fully charged and SHOW IMMIGRATION THE ANSWERS, before they deny you entry.
To be fair:
Immigration is allowed to ask you:
Proof of finance, 20.000 Thb or equivalent currency in CASH
Proof of onward travel within the period you get stamped in
Proof of accommodation.
IF you can NOT show, you entry into Thailand might be denied and you could be send back to the country of origin of your passport ON YOUR OWN account.
You are 50, so you can apply for the Non Immigrant O visa based on being over 50 years of age, get 90 days of stay and apply before ending for the 1 year Extension of Stay.
Wife and kids can apply for the Non Immigrant O visa based on being dependant on a foreigner with long stay in Thailand.