Yurek Hunt. Almost right. From OA to O , you cannot do that in Thailand. You have to break the OA chain so to say. You have to leave Thailand and then you can get a non imm O in e.g Laos, Cambodia etc. at a Thai Embassy, OR come back to Thailand on visa exempt and buy a non imm. O in Thailand.
In my opinion it also depends a bit if you want to come every year and how your timing is. I adviced an Canadian friend to come in on a non imm O and then get the year extension with re-entry, which he did. Every year he comes with more or less fixed timing. Leaves to Canada in March and comes back in october/november. So every year he can take a new year extension with re-entry permit. He can still use the affidavit which is alas not possible for you 🙄. So this possibility to think about, is also a 'money thing'. Banked money in Thailand or 12 times international transfer in your Thai bank account. Good luck !
. Suppose you have a Tourist visa for 60 days in Thailand. After 20 days you have to leave because there is an emergency for e.g. a week in the Netherlands. When you have a re-entry permit, there are still 60-20-7= 33 days left on your tourist visa. 1 extension possible of 30 days so you can still stay 63 days. Suppose you have the same situation without a tourist visa, then you have visa exempt 45 days + 1 extension of 30 days = 75 days. So really not understand 🤷♂️
"The clock" of 60 days does not stop when you leave with a re-entry permit !!