I agree I had first hand experience of being refused until I pleaded with to Senior IO and he agreed to give me 30 days now I have an official retirement visa but that occasion was scary
Chiang Mai is much more farang friendly so you should be okay
Reason why Survanabhumi is so strict they start a lot of Rookie officers there to do training and they are keen as mustard (you can distinguish them because Most of them have 1 strip on their epaulette
If your flying in to Suvarnabhumi airport you will be questioned without a doubt then it will be referred to a Senior IO to decide your fate. Go smartly dressed be polite and smile β¦. May luck be on your side π