To the OPs original question, as far as I know, one can apply for an extension, which subsequently will be denied. But that will give 7 days to leave the country (costs 1900 baht).
I know one can do this from a visa exemption, from which one already have extended once, and from a tourist visa, with the same procedure.
I can't see why doing it from a 12 months extension based on retirement, would be any different.
Thoughts?
Of course, 7 days is not what the OP had in mind, but just saying there might be a possibility if anyone needs 7 more days to leave.