a 3 month statement is required to ensure that it covers 2 full months because a statement for two months now would include all of July and just half of August so not 2 full months
If you mean to get a new Non-O then get the 60 day visit Thai family extension to give you 5 months stay that may well not work the second time as Immigration may insist that you get the 12 month extension. Will your Immigration Office allow this?
You are wrong, the seasoning of 2 months is not required for the initial 90 day Non-O visa but for the 12 month extension of stay. The proof of 40k needs to be from an Embassy affidavit or from Thai wages definitely for the first year and for all years with many Immigration Offices.