12.5" is too big. If the screen itself is 12.5", then the total laptop width (if the screen is 16:9) will almost certainly be bigger than that. Like I said, my primary workspace is limited strictly to a max of 11 inches.
…Unless you knew that and I’m completely misunderstanding you. Which, mind you, is definitely a possibility. Lol. So, I’m sorry if that’s the case and I humbly would ask you to elaborate. ;)