I'd be inclined to try and get a single non-O based on over 50 (aka retirement). You presumably have 800k in a Thai bank? Should be able to get an e-visa when you get your new passport. Then you can enter on that and restart the extension process towards the end of the 90 day entry.
And if by some chance you actually did have a non-OA I'd forget that and still start over with the non-O, avoids the pointless insurance requirement.