Its not a big deal because it has no further consequenses other then paying 2000b fine the next time you do business at the immigration. don't exaggerate the issue.
Swtching to 65k monthy income is only working if you can show a full year of transfers. So you need to start at or before you get your full year extensuon and wait one year.
Bangkok Bank has stricter requirements for opening accounts for foreigners, particularly those on tourist visas, including the Destination Thailand Visa (DTV), as it's considered a tourist visa.