@Dominic ***
yep, it's definitely a personal decision, although I know a LOT of people on the O visa/extension who just transfer the 65K baht a month into their thai bank account from abroad for 12 months and use monthly income that way to get the year extension.
OFF TOPIC:
one guy I know transfers in the 65K baht a month from his bank account in Cambodia, then takes it out in cash, goes to Dee Money and sends it back to himself and then does it again next month.
He's done that now since his embassy stopped issuing income affidavits and not had any issue at all getting his extensions. He says the small amount he loses in transfer fees is totally worth it to NOT bank the 800K baht here