I’m back next month and have purchased a ticket to travel out within 60 days (which I won’t use) from Don Muang to KL, it cost me 1100 THB, or in the past I’ve used Onwardticket.com to buy a dummy ticket for around 500THB.
I got asked by Emirates and by Thai Immigration last year year, and my friends got asked by Qatar. On my too many to count travels into Thailand, I’ve been asked 3 times, it’s hit or miss.
Buy a cheap ticket for a 60 day stay don’t use it, and go to immigration For your 30 day extension, I bought a cheap ticket for 1100 THB Bangkok to KL.