[diggan]

> it's also the case that there are no border checks within the Schengen area

While this was true before, it's increasingly not like that anymore. The border between Spain-France has historically been easy to pass without proper checks, they are checking more and more individuals crossing the border. As I've been told, the increase is happening across other borders (in EU/Schengen) as well.

While sometimes they don't check at all, it's possible they do random controls. So keep in mind that you might not be able to pass the border without proper identification.