THERE IS NO CHARGE FOR A ONE DAY OVERSTAY AND IT HAS NOT BEEN CONSIDERED SERIOUS IN ANY WAY. I HAVE HAD AN IO AT THE AIRPORT MAKE LIGHT OF IT SAYING WITH A SMILE SOMETHING LIKE WHAT A NAUGHTY BOY YOU ARE. I HAVE DONE IT AT LEAST THREE TIMES OVER THE LAST 17 YEARS WITHOUT ANY REPERCUSSIONS SINCE APPLYING FOR OR EXTENDING VISAS.
I'm speaking from experience over 17 years. I've done it at least three times entering by land and air many times since with various visas and had no problems. Also the arseholes at my local immigration office thumb through my nearly full passport over and over again trying to find something to find fault with but they never can because I am totally legit.
I have done this many times over 17yrs to stay an extra day before my return flight. There is no fine for one day and you do not get a red stamp. Just a small square blue stamp with a squiggle and never had any consequences.
Well that 2 hours will probably be taken up with a security check when you disembark followed by an identical security check before you board your 2nd flight. This was my experience when Gulf Air added in a 2nd stop at Singapore from BKK to London last April.. What made it more absurd was that the 2 security checks were at gates right next to each other separated only by a glass wall. And no staff told passengers not to bother putting their laptop, belt, wallet etc. away as they would need to take it all out again about 5 minutes later! And I thought that Thailand was the only SE Asian country lacking in logic....lol.