sorry to burst your bubble . . . . you ALMOST got it, yet it is not fully correct
Upon check-in with the airline in the U.S.A., you need to present your THAI passport, not your US passport
Because if you try to check-in with your US passport, you will either need a visa for Thailand, or the proof of onward travel within the 60-days visa-exempt you will get stamped into Thailand using a US passport. The airline is required to check
After check-in , you LEAVE the USA with your US passport
??? Exit Thailand with Thai passport ??????? . . . . . . . . . This needs a slight correction, because you forgot something:
you cannot check in onto a flight from Thailand to the USA with your Thai passport - a Thai needs a visa for this purpose, or a stay permit for the USA stamped into the passport
So, the correct procedure is: Check-in to the flight with your U.S. passport, and exit Thailand through Immigration with your Thai passport
R. Lagas already smelled the rat. The rule is: as long as you have a still valid visa or a still valid stay permit, you need to cancel it before you are free to apply for another type of visa
because embassies and immigration are run by two different ministries, and actually don't communicate much with each other. The threadstarter is soon about to find out that he will get a problem, because he didn't cancel the ED-extension of stay, before he applied for another visa
The core of Tod’s statement is that you can use the 60-days visa-exempt entry back-to-back for an unlimited number of entries.
That would be a step back to the 1980-ies and 1990-ies.
The assumption is based on a statement of only one single immigration officer at a land border crossing. And I reckon we haven’t received any more such statements, so far
And the holder of the passport was a Filipino - they are indeed allowed to enter Thailand unlimited times, entitled so as being a citizen of an ASEAN country.
of course one could say, since the agent route is considered illegal by many, that Khun Ron proposed to do something illegal by going the agent route if you don't have the funds on your own. Yet, nowhere in the police order it's stated that it is forbidden to borrow the money you need in your Thai bank account
Khun Ron actually recommended the fully (!!) legal route to a 90-days Non-O visa and from there to the 1-year extension. If you want to find people promoting something illegal, go to those who have proposed to use an agent without having to show own funds