actually you are right, renting AirBnB ist more economical, when one realizes, as you correctly mentioned, Thai landlords tend to keep the deposits. I never thought much about this aspect
maybe move into a hotel a couple days before you apply for the extension. Ask the hotel for a printout of their TM30 registration of you at their premises. Show your middle finger to Immigration for asking for 2) and 3) which is an obvious harassment - an unnecessary chivanery because you are already propery registered by a TM30 and they can see the owners name and house book number on their computer. If you can get an official lease contract set up by the AirBnB landlord and his title deeds copy, then try that route. Your experience serves as a good warning not to rent AirBnB premises from "shay" owners, instead of getting a "real" rental contract for a condo or a house from a landlord you can physically touch up with any time
some embassies wait with issuing the METV until 2 or 3 days before the flight date you entered into the application. By this they intend to save for you as many days as possible of the visa validity, which is six months from the date of issue
okay, then you got plenty of admitted stay left. No need for a border run. However it would be a good idea to ask Ranong Immigration, just in case. You cannot border bounce to Myanmar up north. You would have to use a land border to Laos. However it's the same over there: They will tell you to use an airport and fly to Laos instead, as on some borders the Thais won't allow you to make a same-day border bounce. Check a few visa advice groups on the latest news
You should visit the border Immigration in Ranong ASAP (as soon as possible) and find out if they allow you a same-day border bounce. If they say NO (and they probably will) then you need plan B and fly to Vietnam or Laos and stay over there for a while before you come back
You would soon find out something very surprising . . . . . . . . in Ranong, Immigration will not allow you to exit Thailand to take the boat to Kawthoung/Myanmar, if you plan a same-day border run. They will tell you that you won't be allowed back into Thailand, and that's why they don't let you exit Thailand. They don't want to leave you stranded in a land where a civil war is ongoing
and I said I show them a printed TDAC at the airport, because I will need a printed copy anyways when I go for my extension application. A printed TDAC will be accepted at the airport, no need to carry it around on an electronic device that can break down or crash at any given moment