@Brian ******
, okay, the answer is YES you can indeed go from a 30 day visa exempt entry to a 90 day Non-O visa based on marriage to a thai at the Jomtien Immigration office.
You need at LEAST 15 days left on your current entry stamp (or an extension from it) So if you don't have that time left on your stamp you can't do the conversion :/
GO to the immigration office, get the check list from them that lists the documentation you and your thai wife need to provide so you can apply for a 90 day in country Non-O visa based on marriage. It cost 2000baht, you apply, it goes under consideration for 14 days and then you go back to get the Non-O visa and a new 90 day stamp inked into your passport.