Under the proposed rules the 'previous years income' loophole/rule will not apply in 2024. Its too late to do much about 2023 now.
In retrospect, what expats should have done for past 40+ years is what you say.
In say 2015 open an account called 2015 income. Place enough money for 2016 expenses into account before end of december 2015. Taxed or untaxed money, doesnt matter.
On 1st Jan 2016, transfer all it it to thailand. That money is previous years, so no tax on it. Nothing about is it pension, interest, dividend etc. Easy, using loophole !
Start a new account for 2016 income and repeat
The few lines of transactions on the bank statements would be full proof of your compliance with the rules.
Looking back on this, I am now shocked that this was a well known process for expats. Many advisors, web experts out there. Why was it not well discussed ?
Probably as RD didnt pursue us for tax. But they could have, and could look back to older years if they wanted too.
Maybe worth doing a 2023 account, just incase they repeal the new change.