About Night 6
This probably requires the same about of luck, but I've managed to beat it this way:
Instead of checking the doors with light, I've checked both hallways on the camera, since it doesn't drain power unlike doors or lights. Basically, I was switching between 2 cameras about each half of second, then after 4 seconds, I've checked the girl behind curtains (like in FNAF, you check on her for 0.5 seconds each 4-5 seconds).
Once you see one of the maids in either hall, be ready, once they disappear, close the door and check the light. Sometimes they just leave to another room, but often, they go from the hall to your window, so better safe than sorry.
This strategy allows you to conserve a bit of power, while also knowing whether the milf is threatening you now or not (if she's in the hall, she'll most likely go to the corner, so be prepared to close the door when you hear her step). It may not be a lot if you only turn on the light for a split second, but in Night 6 every drop of energy counts.
The Nameless (the one with music box) only appears in cameras 6, 8, 9 and 12. Look at her to make her disappear, but make sure you're safe when you do it.
Even then, you'd need to be lucky, since you're most likely to run out of power, so pray that you'll get to 6 am before you get a game over.
Hope this helps. Good luck.