so do find that sometime banks just say that sort of thing to get rid of you but it’s hard to argue with them even when we all know non o is nota tourist visa 😀
You will be able to open a bank account without issue if you get a non - O visa before you leave your country. Once you arrive in Thailand open your bank account and transfer the money ( I did it bank to bank using Swift codes) Make sure you label the funds ‘long stay’ or equivalent on the transfer