@Tullio ******
you'd have to check with your office because some offices just won't accept combination method (even though it is allowed) and for the monthly income you just need the 12 months of transfers before you apply for your extension
GO and talk to the office tell them you have 11 months of transfers DON'T tell them you have 800K baht in the bank and see if they'll let you use monthly income with just 11, they either will or won't