@Brandon ***********

thank you. When I went to Thai Airlines check in desk they said it should be fine. I will have all the documents explaining the plan of 60 days plus possible extension of 30 days.

If not, I can always buy a return ticket on the spot from Thailand to Vietnam (where we want to also visit anyway but wanted to wait to check a period of good weather) for a few weeks, before returning to Thailand and exit on original return ticket.