Infection was mid of June 21, Released from quarantine mid of July, recovered certificate is valid until mid of Dec 21. Vaccination of 1 dose in Dec = certificate of fully vaccinated. Is it possible to enter Thailand with the test and Go procedure (1 night in SHA+)?

yes, 2 weeks after vax.

for j&j 21 or 27 days.

I would speak to a doctor sometimes before getting jab, if antibody test can be done (they are cheapeesh, 1k) and certificate extended. Just as a back up, if any rules change, for example is your jab brand turns out ineffective, substandard