@Marcus *****
I'm not going to say you should get a cheap hotel room and have them file the TM30 for you, because that'll be unethical since everyone should always have a TM30 on file... IF the immigration office requires the TM30.
My advice would be to post this question on a Chang Rai group and see what their requirements are for a 60 day extension of stay based on unable to travel due to COVID-19. Most immigration offices do require the TM30, but some don't.