I did all that last year, 65,000 religiously, got letter from the bank confirming o’seas transfer. Was still required to get letter from embassy confirming that income, which they don’t do. Also I wasn’t in Bangkok so wasn’t going there. Ended up giving up and sticking to the 800,000 method.
If you post your passport ANYWHERE it’s likely to be the last time you will see it. I think the only place you should let it out of your sight is at an embassy or consulate.
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