Used to fly XC up to that area from EHBK (think the island was called Ameland or something) and was warned about the Dutch equivalent of RSPB being anal in the extreme. They would report anyone whose number they could read as a matter of routine. I think my N reg PA-28 probably helped there. To be honest I was more concerned keeping under the Class A 1500' limit. One trick I used was to pop into Budel (EHBD) on the way home and do a couple of T&Gs. Get lost in all that ATC chatter.
