I did it on line. I went to immigration at Samui with the form and they wouldn’t accept it. They said to do it on line. The TM 30 clearly mentions the occupier.
Ya get stamped in for 30 days. Can go to Immigration and pay 1,900 baht for a 30 extension. After that, you need to make a border bounce for another 30 days. Not sure but after that, I think you can pay another 1,900 baht at Immigration for another 30 days