I think it's fairly clear. If your embassy doesn't provide proof of income, you can't use income to start. You have to have 800k in the bank for a non-o.
The bank issue is also fairly clear. It's nigh impossible to open a bank account on a tourist visa. So get a non o before you arrive, open a bank account, put 800k in it.
If you want to switch to the income method, start depositing 65k from abroad every month. Just make sure you meet the requirements for both the 800k and the income methods that entire year.
Most of the confusion is because people generalize when they should be specific. A non-o is not the same as a non-oa. A dtv or other tourist visa is not the same as a long stay visa in terms of being able to get a bank account.
You can do whatever you want with the 40k you deposit monthly. Spend it all the day it comes in, if you like. However, the first year, you must continue to meet the 400k requirement as others have explained, and in addition deposit 40k each month, from abroad. You are probably right about the pension thing. Some offices require it for a retirement visa, and I probably got that mixed up.
this is true for the first year, but not for subsequent years. You can use the monthly method of depositing 40,000 baht after the first year, even if there's no embassy letter available. by depositing 40,000 baht each month, from abroad, during the initial year. I don't know of any office that forbids this but there could be. I understand some offices want to see that the funds come from a pension (I the pension part is incorrect here, but I'm leaving it in as others have commented on this aspect).
I'm with Wylie. I moved 7 years ago and never transferred my Bangkok bank account to my new location. I can order yearly statements from the mobile app, and the local bank does the letter in one day. Just use the mobile app to withdraw money, and avoid the charge for using the ATM card out of your bank's free ATM area.
I don't put in a reference number when using Wise. I use the mobile app to email a year's worth of statements (so I don't have to wait a week for the bank to send it) and go to the bank for the letter. No problem for April, which was the last time I did it.
there is no change to the Thai immigration rules about the monthly income. But different embassies may have different rules. Perhaps they have a little cushion built in in case exchange rates change.
I have heard that some immigration offices will check the source of the funds and want it to be a pension. Others don't. Check with the specific office.