I have some interesting information for ppl holding a Non-OA visa.
If you have got the visa recently you may have noticed a new "Remark" section in Thai(?). It actually states the expiry date of your health insurance.
I have asked the Embassy in Copenhagen what that means in real life?
The answer is that you do not need to have health insurance for the full year as before, but can choose any validity period (6, 8, 10 months). When entering Thailand, you will get stamped in for as long as your health insurance is valid (up to one year).
It actually means that you dont have to pay for 1 year health insurance if you only stay Thailand for a shorter period of time.
If you want to stay longer (up to one year), you just need to visit the IM showing your extended health insurance. And yes, they do accept foreign insurances also, even they might want to see a translation of the Police into English.