Hi mod legendkiller !
Actually, i've read your request, and i'm afraid to say something which probably destroy people hopes, and my own :
with this last glitch i found to go in a dark area, i'm now absolutely sure of one thing : If a District is black, it needs a loading sequence.
Those "strange doors" i mentionned show it perfectly : even if a huge door can be opened from a known district to a dark one, you couldn't see, and go through the dark one if there is no loading sequence, because of the fact that, if you are in a specific loaded district, every other district doesn't exist during this load ! They appear only when you've got a loading sequence (sorry for repeating, i'm searching english words but i can't find them ! (Damn French education system !) ).
So, if we can go into one of those
black districts, and not just a black area in a known district, it's not by glitching like i actually do.
... Sorry, it's very hard to me to proove a fact that i was afraid of ...
Good Night !
Tepec, 11:47PM, time to sleep and count the grunts