I invite you to comment on https://docs.google.com/spreadsheets...it?usp=sharing or, if you want, I can give you edit permissions. This is my sheet collecting the airline baggage size info.

40 x 30 x 10 is even harder than my favorite 40 x 30 x 20. I did an infodump of those over at the EDC forum: Recommend “personal item” size pack. You will find the Cargo Works 15" Macbook Pro EDC backpack (38 x 27 x 6) mentioned which is well within your desired limits. Plus it has a ton of MOLLE so you can add more pouches to it.