but you have to have the 800,000, the extension on that basis, complying with that extensions rules, whilst you bring in the 65k every month. On the second extension you can then switch.
the point is, you could decide not to attend an appointment or an appointment might not result in treatment. So if you are applying for a DTV based on medical treatment then it's best to show proof you are going to receive treatment.
how did Bangkok hospital diagnose and quote for treatment? Did you attend an examination? Perhaps speak with the hospital and get an agreed treatment plan in place, with costs, and deposit. That will prove you are genuinely a patient who's going to receive treatment. My son had to pay a deposit to the hospital before he was treated so I'm sure Bangkok hospital can do the same.
You need to use this visa before it expires in July! Once you've entered you get stamped in for a 60 day visit. It's multi entry so you can leave and re-enter for 60 days.