flyer 43 is right.
Now that Westy has provided hard information, it rather changes the picture.
If things are as quoted, it might well prove difficult to do what you suggest within the rules. I am not saying what was planned was wrong (I don't have all the info), and I am not familiar with the German variations to the EASA/JAR rules.
If I was involved, I would be looking for another better nearby site, just from a general risk perspective.
If the German CAA did not give the flight permission, then I guess that is what the operator did anyway