See this screenshot with GE Pro: D2 it's 36.32 meters wide, and we set it 36.0 meters in the scenery and the GSX customization.
I guess in reality they might send a 747 there, by being sure nobody will go to the two nearby parking spots but, unfortunately, the AI engine of the sim doesn't support this so, if we did something like this in the AFCAD, AI will clash one into each other.
But if it's just to park your own plane, you can of course override the setting with the GSX parking customization page, so the AFCAD size will remain the same (and AI won't cause problems, although you will never see a 747 AI there), but GSX will allow to park there.