What are the documentation and bank balance requirements for applying for a 1 year Non-O spouse visa while in Thailand?

This is the general information for an in-country Non-O visa based on being married to a Thai national. Go to your local immigration office to get the latest handout for office-specific requirements.

/6.FOR-PROVIDING-SUPPORT-TO-OR-BEING-A-DEPENDANT-OF-A-THAI-CITIZEN-SPOUSE-VISA-NON-O.pdf

This is what you need to get an extension of stay based on marriage. You still need to first get the Non-O visa

I suggest you go to your immigration office and get the hand out listing the requirements

There is no one year Non-O visa issued based on marriage to a thai inside the country 🙁

You would first go to the immigration office and apply for the 90 day Non-O visa based on marriage by showing 400K baht in a thai bank account in your name only and providing the documentation for 2000baht. That will go under review for 2 weeks (or more at some offices) and then you go back to get the Non-O visa and a new 90 day stamp inked in

After that you wait until the funds have been in the account for 2 months and you have 30 days or less left on your new 90 day stamp then you go back to the immigration office and apply for the year extension for 1900baht. That will go under consideration for 30 days (during which time they could visit your house) then you go back and get the year extension inked in.