I don't know, there's been several reports of Bangkok Immigration no longer accepting income affidavits from any country, so we might be seeing a shift in policy
So you can no longer use the "income affidavit" method, you'd be better moving onto the 65k per month international transfer, although you've left your run late for this year, so you'll have to swallow the pill and transfer the 800k for the first year, but make sure you start the 65k transfers immediately, so they'll be in place for your next extension