Emirates, IATA says , as you can fly, same ruling as IATA
Extension of stay is possible.
Passengers are allowed to enter if their stay will exceed the actual visa-free period as long as they hold a return/onward ticket.
Warning:
Visitors who are visa exempt but do not hold return/onward tickets could be refused entry.
E visa site, they give you approval as you can extend ! Only as a SUGGESTION they come up with a visa to order.
And that is a very official site.
With a Tourist visa, you can stay in Thailand for no longer than 60 days. If you wish to stay in Thailand for more than 60 days, you can extend your stay with the Immigration Bureau. Suggestion : You may apply for visa at the following mission(s)
Royal Thai Embassy, London
See video from George (deeper dive) page 11 and scroll down:
It all should be without problem , entering Thailand and extending, according Nurachai Ninnad, Deputy director general of ministry of foreign affairs. Every time it is said.
However there are air flight companies , blocking you. Like KLM and EVA air.
KLM demands a visum and EVA let you sign a contract, they are not responsible if you get refused.
With all reading, I also decided to fly Emirates on exempt with having a return ticket on april .
It should be enough is my conclusion and sure hope the IO also approves.
Just red BilliBobsteeth experiences about doing borderruns, he pays 2000 Baht to have a new 60days exempt but not staying in Malaysia. https://aseannow.com/topic/1339320-border-run-to-wang-prachan-malaysia/#comment-19267306
As is said, you should stay out of Thailand for 1-2 days when going for a new exempt.
So by paying 2000 baht, he avoids that rule and get in right away.
Also red a story about another border runner (Laos or Cambodia) and also could get in after paying 2000 baht !
It is not according to rules, but for a farang very handy to know.