Try opening a bank account back home , UK in my case. Then try to take out £5k in cash, you will be asked all sorts of questions so B4 you criticise look at it carefully they are trying to combat fraud.
I have visited several times in one year and not had an issue. If you wanted to play safe get a 60 day visa from the Thailand embassy in your country online, but at the end of the day the immigration officer your appear with is the ultimate determining factor.