Retirement extension holders simply worked out that an annual extension plus a multi entry reentry permit is approx 6,000 baht per annum. Plus, keeping 800,000 baht tied up. Instead, they could get a five year multi entry visa for 10,000 baht with no ongoing savings requirement.
The gentleman is French and applied to Thai Embassy in Saigon, Vietnam. His girlfriend (nationality not stated) applied to Thai Embassy in Jakarta, Indonesia. A few variables there.
You requested advice re; dental soft power. Could suggest book at least half a dozen advance cosmetic treatment appointments (stretch them apart to monthly) in one go. Even at Thai prices the cost may be prohibitive especially if you don’t need the work. There have been reports of applicants doing this and, after their DTV was granted, cancelling their appointments. I haven’t done this myself.