If your TM30 gets registered when you get to CM you should be able to do it there. All I have handed over at the window in CM is passport and TM30. Each time he puts TM30 to side and never looks at it. They scan your passport and all info they require is there. PS: it takes a few minutes in CM Airport Branch. Has a drive through if in a car or on a bike.
Anonymous participant They can reject your application. They can see on their system if you are back in Thailand. Look through previous posts about this. They can ask you to prove you are still in Vietnam. If you are a remote worker what is the need to rush back to Thailand is a question they may well ask themselves when assessing your application.
Make a list of must havea and nice to haves. I put things like Govt Rates of electricity - Landlord/agent does TM30 and after any travel. Wifi must be fast and fibre.
I think we are talking about a different guy. There was kne where they wanted him to return to UK and it woukd be issued. Had to show boarding card etc from Thailand to UK etc