Unless you are trying to avoid the insurance requirement you don’t need to switch to a non-O. You can renew your insurance and extend the OA for 1 year inside Thailand.
I was able to get my insurance company to coordinate my policy dates with my visa dates. Instead of trying to get a few days of insurance you should be able to buy 1 year + a few days.
This is one of those things where even if you don’t know the answer you can do with almost no effort and cost. Just do it. Bring it with you. If they ask for it then you have it. If they don’t ask for it they you aren’t out anything.