Both are okay. First affidavit I got was the 2 months deposits on my Dutch bank and my second one where 2 months deposits on my Thai bank. But again, that's the Dutch Embassy. You really have to look on your own Embassy in Thailand.
But you are much too quick. If you have the 'O-A' then enter before 30 sept. And you already have an extra year as James Miller stated ! Rules can change in one and a half year....
Just a thought: Can't you come in on a 30 exempt entry (30 days) and extend it by 30 days at an immigration office ? When you only want to stay for 60 days.
Tod, just a question. Can you switch the income reasons for the year extension ? When e.g. you used banked money before and now use an income statement (65K ฿; Dutch) from the embassy and visaversa ?
Thought so. So that's maybe also the hassle. He did not understand the problem. But got back in Thailand already with a 60 day stamp. So don't need to correct the first stamp I guess.