At the airport 1 day overstay is often waived, especially if you leave in the early hours of the morning, unfortunatly i think you will get the full two days. But it's only a 1k fine, and no hard feelings. Mistakes happen and people overtsay by a day or two all the time.
Correct. Pay the money, sign the paper, smile, no problem. It's happens all the time. It's the big overtsayers and people who do it again and again they don't like.
If you are one day overstay at the airport they often don't even fine you the 500 baht, you get a little stamp saying it's been waived. I wouldn't worry about it.
(Chiang Mai, leave my house at 7.45, arrive immigration at 8.00. Opens at 8.30, out the door at 9.30, back home at 9.45..........no, that's a lie, I always stop for a beer on the way back,