This does raise the issue of flying with the logbooks in the aircraft if the maintainer is not at home base of course.
Did you know there is a "JAA approved" fireproof container for carrying logbooks?
Not kidding!
Or we could all go N reg.
That would actually be quite smart.
Although, paradoxically, it is easier to do a lot of common avionics mods under EASA now, because the NY IFU has washed its hands of 337 approvals so forcing other, potentially much more costly, routes. Well, so long as you install products produced by the Owner of the Known Universe (Garmin).