Can I apply for another extension on my tourist visa or do I need to exit Thailand?

@Steve ********

okay first off there is no such thing as a Non-Immigrant-O visa type B :O

You can get a Non-Immigrant Type O visa (the O means Other) based on marriage to a thai AND you can legally work and hold a work permit on that type of visa. So NO need to get a Non-B visa.

I would say go to the thai consulate in Savannakhet Lao and get a year-long, multi-entry Non-O visa based on marriage. That consulate does NOT require proof of funds (so you don't need the 400K baht in the bank).

On that visa you will get stamped in for 90 days, then when that 90 days is up you go to the border, stamp out of thailand, stamp in&out of another country then stamp right back into thailand to get a new 90 day stamp. You do that for the whole year the visa is valid for.

OR

If all you're wanting to do is buy yourself 30 days and assuming you haven't done TWO 30 day visa exempt entries by land yet this year):

go to the border, stamp out of thailand stamp in&out of another country and stamp right back into thailand to get a 30 day visa exempt entry stamp.

From Bangkok the closest border to bounce at is the Phu Nam Ron border in Kanchanaburi province. There are companies that lug people there every day or you can do it yourself.