I was asked at Thailand Airport on arrival , where is return flight and accommodation i asked why are you asking me this, for 20 yrs never been asked this, he got so angry and refused to serve me, said go to to other counter, which I did , passed through without a word
just get 30 days when you arrive then register for another 30 days, if you don't want to queue at immigration, there is someone who will sort it for 4000 baht in the next door office if you are going to Pattaya