Continuing/Maintaining Thai Social Security after Leaving Job

I plan on leaving my job at the end of December (and stay in Chiang Mai), and wish to continue with the Thai Social Security I have been paying into as deductions on my paycheck (for the national health insurance).  Different provinces have different rules and requirements.  When I lived in Trat province some years back and I left my job, it was simple to keep the Thai SS going: I went to the SS office and simply started making payments to continue with the SS.

I have been told by my current employer (after they contacted the Social Security office in Chiang Mai), that in order to self-pay into the Social Security to maintain it, the following is required:

--Married with Thai Spouse (Need to show Thai Marriage Certificate)

OR

--Need to show House register in Thailand (Yellow Book (Thor.Ror.13) /Tabein Ban or House Book)

--Contribute money with social security at least 12 months

--Must to apply within 6 months after resignation

--Over 60 years old can apply.

I’m not married, so it appears I need a Yellow Book (which is for foreigners)

Two questions:

1) Has anyone been in the same situation, i.e., wanting to self-pay into the Thai SS system after leaving a job… and have done it?

2) Did it require a Yellow book (if you, too, were not married to a Thai national)?