I wish I had read your post before applying for my yearly extension last week. Six months ago when my O-A ran out I was granted an extension of stay based upon retirement until my insurance expired. I am also married to a Thai. I will definitely go down that route next year. To satisfy O-A visa requirements I purchased a health issurace from the approved list. Gave a huge excess that renders the insurance usless but cheap then bought a sensible policy with high inpatient cover
The TM30 issue is confusing as every immigration office has its own set of rules. Being a good lad I went to Korat Immigration and they told me only if I leave Thailand do I have to do again. My mate who lives in Chang Mai wasn't so lucky. Got fined 800 Baht