I had remembered you posted this. I am assuming that if immigration is closed tomorrow that also mean the TM30 office inside correct? In Chiang Mai they have different open hours for both.
If you have the letters from the university it means that it has been formalized by the department of education and you have a small window before those documents expire I believe. So at this point I don't think you have too much say on extending anything.
Thanks for confirming that Robert. My followup would be this. Technically I applied for my first ED visa and was approved October 30th of 2017, so could I go back? In addition it has been longer than 1 calendar year since I had it, since I have been on a tourist exemption for 67 days.