Peru, Chile, Argentina, Brasil and South Korea citizens get 90 days exemption visa entry stamp by air or land, but I am not sure If Mae Sai do that. I heard about some argentinians that were denied to cross the border and the officials invited them to go to Chang Kohn or Nong Khai. They said that is ok a border bounce there for 30 days, but not 90, don't ask me why.
I'm not playing anything, I just don't like that somebody think I am a lier. If I say I know a lot of cases without any problem in Chiang Mai and Mae Hong Son is because I know them. If somebody say "hard to believe" sounds like I am saying a lie, which is totally impolite and unrespectfull. But you judge to me, and not to the person that insult me, well done Mr Admin.
So, if you don't believe me is your problem. More years than you in this country but still I don't play games about who knows more, just said what I know.