This is ugly when occuring randomly in the Common.js (at worst multiple times at different places). Of course, the best way would be to store it on the server and load it simply server-site, but I was told by the support that they are not going to to this.
The object could be stored in mw.custom or wgCustom or something with a completely new naming. The page could be namend Special:CustomConfigVars or something similar.
What do you think about that? Thanks in advance for your feedback!