Yes, this was a big problem for us. Well, mostly for DW.
We made a very dark room by buying the padded 14" squares made for the vent recesses (there are two, one in the bedroom and one in the shower/lavatory area and we also got one for the toilet stall, too. Then for the side windows next to the bed we cut silver bubble wrap to size of the side windows and slid them behind the shades to keep them in place. Finally for the area you are concerned about we keep the door to the rest of the rig closed and for the shower dome (where the light comes in and makes the pleated door worthless), I stapled Hook & Loop to the dome's frame and adhered the other side of the Hook and Loop to an oversized piece of silver bubble wrap. We attach this each evening as part of our getting ready for sleep. When the bedroom door is shut the room is very dark and stays that way until we wake up and remove things. But the night's sleep is awesome and well worth the effort!
There is a more expensive sliding shade that can be mounted to the dome but we took the cheap way out. Being able to remove the silver bubble material (it is folded and stored in a small place between the lavatory and the shower stall) means it does not affect the shower or vice versa.
Your layout may vary, but this is what we ultimately used to keep things dark:
Vent inserts -
http://www.campingworld.com/shopping...-cushion/26552
Window covering material -
http://www.campingworld.com/shopping...pose-foil/5818