We did the same, at the airport agents told us no big deal we went through with no issues , no overstay , no fine!

Steve you will need a digital arrival card which you can get online 3 days before entering Thailand (it’s free) lots of scams online trying to make you pay, find the free one , you will get 60’dsys to stay in the country. Then jump over to Vietnam before the 60’days is over . You will need a visa for Vietnam , that visa is $25 per person . Apply in advance for sure , you cannot fly to Vietnam without it, it takes about a week to recieve via email . Then go back into Thailand and finish your trip, remember you will need a new Digital arrival card every time you enter Thailand (the free one) so reapply 3 days before entering Thailand again when you renter you will be given another 60days .

It’s only $12,000 not $400,000!

@Baz ********

thank you !

Baz Wallace do you know if it's possible to leave Vietnam after a 90-day stay and then get approved for another 90-day visa once we leave and reapply? Or is there a certain amount of time we should wait ? U.S. passport

Might have been a good idea to be informed before you invested money.