@Austin *********
as you are on an extension of stay you won't be changing ANY visa (you're not on a Non-B now and you won't be getting a Non-O)
All you're doing is changing the reason for your extension from one based on employment to one based on marriage to a thai.
Go to your immigration office with your thai wife, get the hand out listing the requirements for a year extension based on marriage. Get a letter from your employer stating they know you are switching reasons to an extension based on marriage and have no issue with it and then when you have 30 days or less left on your current extension go apply for a new yearly extension based on marriage for 1900baht. You'll get a 30 day under consideration stamp (they might do an in home visit during that time) and then you go back to get the year extension inked in.
People change reasons for extensions all the time.