has confirmed they’re still able to assist you with a bank account if you’re on visa exemption or tourist visa and apply for a Non O in country with them as a total service. I know a couple of other too.
You can apply in country, but you’ll need to apply through a visa company that are able to open a bank account for you as an example the owner of this site and they will open a bank accounts for you as a service in a total package with Non O visa in country and your first extension of stay.
You can, but as everything has turned out now, you’ll need to go through an agent to be able to open a bank account to prove that you fulfil financial requirements for a Non O visa based on marriage. Better odds to do as Graham advises you.
Normally a receipt of your TM.30 address registration and your lease contract should be sufficient for the extension. If you don’t have a TM.30, you’ll need a copy of the housebook, rental contract and landlords ID-card to do it yourself before you apply for the extension.
Then you’re not applying for a one year Non O-A visa, but a regular 90 days Non O visa. You should be able to get a bank account and bank the required 800K baht within some weeks in time to apply for your one year extension stay, but you might have to visit several branches or use an agent for a "quick fix".
Apply for a Non O e-visa based on marriage through the embassy before you go to Thailand. The process it’s quite simple and cost normally around 80 USD. Visit the immigration you will use in Thailand and get handed over a list of their specific requirements for extension of stay and collect all documentation you’ll need to apply. Cost is 1900 baht.
Do you have a monthly income/pension of minimum equal to 65K baht (€1755)? If so your embassy/consulate in Thailand offers to provide you an affidavit letter you can use at the immigration and apply for a Non O based on retirement in country with monthly income. Otherwise there’s no legal way around the financial requirement for long stay in Thailand.