Just wait it out. Personally, if I was in tax resident status and not actually earning money here I wouldn’t get a TIN or file anything until I was forced to. These changes are for catching high net worth individuals who are evading taxes, not your average expat.
If the money is hitting your Thai bank account and you are here longer than 180 days then you are obligated to report it. That doesn’t mean you have to pay taxes on it though. Best to ask a tax professional though.
Be aware that local banks will likely start reporting significant money transfers soon to tax authorities to bring them in line with international standards. There is a huge push now to crack down on money laundering and to a lesser extent tax evasion. Pieces are being put in place to automatically identify violators in the near future.
I used a letter of employment from my HR that clearly states I'm a remote worker. Applied through the Thai Consulate in Los Angeles and had zero issues.
The airline desk staff had no idea what mine was. She had to call a supervisor over who then took a picture and presumably sent it to someone for validation. Took about 10 minutes. My wife is Filipina and tried to explain in Tagalog, but they had no clue what a DTV was.
In Singapore last year Singapore Airlines refused to let me board without a return ticket even though I had a DTV. I had to step out of line and buy an onward ticket to satisfy the desk agent. They didn't dispute the visa, just the requirement for onward travel.
I'm not sure how random airline staff would scan it anyways. They would need access to a system from Thai immigration to validate the QR code on the visa and I kind of doubt they have that.