hi. I extended my STV today successfully. I provided my property lease papers, my original insurance which I purchased in the UK. Vaccine certification, TM7, TM2, two photos.
Yesterday I purchased Tune health insurance (Thai) in order to extend. I leave Thailand on April 5, so took insurance out up to this date only, at the cost of 2780 bhat.
I wasnโt sure immigration would go with this but they did. They stamped my passport til April 5 as per my insurance and request. Some immigration offices are requiring the full 90 day health insurance to extend an STV, but that wasnโt the case for me.
I hope that helps. I think I have put down everything you need. Good luck ๐ค๐พ๐๐ป