Just returned from Chaengwattana (Counter J) after applying for a 60 day extension due to Covid-19. Process was smooth overall but they did ask to see my return flight itinerary back to the USA. If you have a return ticket definitely bring a print out of that. They did also seem to look more closely at my address as compared to last time and they even printed out what appeared to be a TM30. They did grant me 60 days even though my flight leaves before that.
TLDR : Answer Summary
A user shared their experience applying for a 60-day extension at Chaengwattana (Counter J) due to Covid-19. They noted that it was a smooth process but emphasized the need to bring a printed return flight itinerary back to the USA. The officials appeared to scrutinize the applicant's address more closely than in previous visits and even printed out a TM30 form. Despite the return flight being scheduled before the granted extension, the user was still approved for the full 60 days.