In regard to using TransferWise and similar companies to transfer funds to Thailand where you need to show immigration that you are making international payments, there are two issues, some companies do not transfer the money, but have local accounts and just pay from them, therefore no international payment is made.

The companies that do transfer money can use different routing some times it is direct but other times they use the Bank of Thailand BAHTNET, this is clearing house for payments, when paid this way it will show up in your account as a local payment, however, for Bangkok bank I've seen that some people have been able to get a statement showing that the payments are international from the main Bank, I don't if it's true but it's worth looking into.