With the greatest of respect, Jim, this is a senior partner at one of the most prominent Thai firms in Bangkok. He's well connected and makes things happens. He's made things happen for me for nearly thirty years, so I would hope you'd understand why I have have more confidence in his interpretation of Thai law and his judgments as to their application than I do in yours. I think it's generally foolish for foreigners who aren't even qualified lawyers to trumpet definitive opinions as to the meaning and application of Thai law. Respectfully.

Yes, the lawyer who has handled immigration matters for me in Bangkok since the 90s also told me that he could arrange for the DTV visa to be issued here without leaving the country if I wanted to switch. So I gather it’s at least possible, although I don’t know if it’s a ‘general public’ thing, or just (as with practically everything in Thailand) a ‘with the right connections’ thing.