Yes it happened to my cousin in Phuket. Immigration came knocking on his door at 9.30pm asked to see his bank book. Game over. He's on year four of his ban
So you use the 65k monthly transfer method like I've done for nine years. I'd never use an agent. If at any time you're asked to show your bankbook and there's no 800k it's instant overstay, arrest, deportation and five year ban
A huge pain to apply for? And yet you're happy to border bounce perpetually hoping to God you're not going to get refused entry and get a black mark on your immigration record? Your call I guess.
New bank reporting rules introduced in April this year has been a very big clamp. Over the years I've had about six different accounts, never been a problem. A couple of months ago I wanted to move my branch to another branch (both within Bangkok), but caused too many issues so I just left it as it was. Certainly not as easy as it used to be
You can't convert a visa to Multi-Entry. All you can do is get a re-entry permit which allows you to re-enter on your current entry stamp. This can be done at the airport, takes ten minutes, better than traipsing to an immigration office to do it