Originally Posted by
Scandinavian traveler
Called iberia who said it was no issue, but the guy did not seem very knowledgeable (e.g. said I could “fly he entire world” if I just put my first first name and my last name), and I am therefore asking here to confirm.
This is essentially correct, as a general rule one does not need to bother too much about middle names when travelling (and for a lot of people in the world it is simply impossible for their passport name to match the boarding pass exactly).
However, I would not use your solution. I think it is better to drop or abbreviate one of your first names, rather than writing one of them as a surname.