Not sure what you are trying to say but as land borders are open you can travel to a neighboring country, the closer you are to a land border the more likely you are to be rejected for a unable to travel extension.
Far easier to do it in country than back in your own.
60 day tourist visa, extend by 30 and apply for the Non O based on retirement when you still have more than 15 days left on the 30 day extension. Then the 12 month extension to your Non O Visa.
Gives you time to find a good place to live, sort out all the financial stuff and used to dealing with immigration.
Of course, it doesn’t give you a Thai Pass, ability not to do Test & Go or any other restrictions that may be in place at the time. It just gives you the right to stay, in this guys case, until May 16th 2023 whether he leaves or stays. Just needs to be back in the country before that date.
Get the year extension then when you leave Thailand buy a re-entry permit so all you have to do is come back to Thailand before the 12 month extension is up.
This gives you the 3 months you want and another 9 months to re-enter to keep the extension alive.
I came to Thailand on November 6th on a TR60 visa using the old COE certificate.
They were both approved and I came on a one way flight.
It is as many people say though pot luck if the check in person for your airline wants to see a outbound/return flight. Just make sure you have a method of booking an onward flight there and then.