You apply at a Thai embassy. You submit a bank statement from any bank. Do you not know how to get a bank statement from your bank's online portal or app? The only time you are required to have a Thai bank account is when you are applying for an extension at an immigration office in Thailand.
First, try the bank where your spouse has an account and go with your spouse. If that fails, you're now playing the numbers game. That means hitting as many bank branches as you can until one says yes. Possibly even going back on different days and talking to different staff members at the same bank branch. Eventually you might find one that will do it.
you will be able to apply for tourist extension all the way up until 20 days of overstay. They'll just fine you, stamp your passport, and then give you a retroactive extension. That means if you go 3 days overstay you'll only get 27 days from your extension because they will date it back 3 days, and you'll pay 1500 baht overstay (500 per day).
But you need to be aware that you'll also be fined for not cancelling your education extension. You'll need a letter from your school that states the last day of study, and you'll be fined 500 baht per day from that day (up to 20,000 baht)