It all seems a bit to good to be true i think. For 10,000 baht you basically get a 5 year visa allowing you to do your remote working? And they arent asking for some kind of income tax?
Im 53 married but still do a similar thing as working in the uk and frequently commuting. I get a multiple entry visa non immigrant O based on marriage. Costs £200 a year but you are then free to come and go as you please. I dont know if this is the best way but im happy with it