@Gregory *******
the thai banks implemented a policy stating that you can't open a bank account on a free stamp or tourist visa entry. You need a Non-Immigrant type visa <- that you can extend long term
That's why I said UNLESS you have a thai bank account already you're idea to show up free stamp and then apply for the in country Non-O isn't gonna work.
You need to get the initial 90 day Non-O visa from the online eVisa system thru the thai consulate in your country (using proof of funds in your country) before you come here.
That will let you open a bank account and transfer in the 800K baht so you can apply for the year extension based on retirement at the immigration office once the funds have seasoned 2 months