After getting in touch with the German military Bundeswehr the situation turns out to be more complicated than @DK9JC and me expected in the beginning. The legal definition of an installation according to the Bundeswehr may in fact cover every antenna set up. In the current state an explicit permit for every activation of Erbeskopf seems to be required. @DK9JC is in negotiation with the Bundeswehr to get such a permit. In order not to spoil this negotiations no activations of Erbeskopf should take place currently.
I have put an explanation and warning notice on the summit page
73 de Michael, DB7MM
SOTA DM association manager