[Tade0]

My experience driving through the EU is that barely anybody cares. You may be stopped at internal borders if your car plates don't match a Schengen-area country, but that's it.

You'll need your ID to stay in a hotel/AirBnB though. So unless you squat or camp illegally, better have it with you.

[vertex-four]

Plenty of places within Schengen where wild camping is legal, and couchsurfing (through platforms other than couchsurfing.com) is still a thing.