Beware that your Border hops overland will be denied after the first two (apparently).
Id have thought youd want to inform Immigration of your marriage because youll need a longer visa based on that marriage- otherwise eventually youll be living apart.
You might have to rethink part of your plan; TH is not open season for anyone and any number of entries.
There are restrictions same as any other country really. But its a multi layered system, just depends what you can compromise on/how much money you want to throw at it.
Shell out a few quid to get a 60 day tourist visa before you leave and you wont need to worry when you are here at all. Everybody that is visa exempt also has this option.
Each extension is a brand new legal document. So you cannot change the premise of your current one, but when you next extend you can use either method.
actually, if this is your first annual extension from a 3 month Non O to a year, in my experience recently the 90 day requirement kicks in 90 days after the renewal date, as confirmed by the note stapled inside my passport
Im just about to do my first after being in Hua Hin for over 6 months on tourist/Non O visas as a result.