Can I extend my Non-O visa for 30 days before it expires instead of doing a 1-year extension?

I think you misunderstand your options,

you can apply for a year extension by meeting the financial requirements WHEN you have 30 days or less left on the current entry stamp.

OR

you can get one 60 day visit thai family extension (again when you have 30 days or less left on your current stamp)

Those are the only two options you have as far as an extension on a Non-O based on marriage.

Also you don't have to lock the money in a thai account, you need to have the 400K baht in a thai account for 2 months before you apply for the year extension. After that there is no requirement to keep the funds in that account.