Thanks guys for the additional and very useful information, and I decided to make a few changes to the mystery compartments. The one that I built to a luggage hold actually consisted of two compartments: A bathroom and a room for electrical panels (switchboards). So I changed this and added signs on the doors. Probably not what it used to be like but it gives an impression.
The bathroom was equipped with a window and I used one of the blinds (included as a feature for each of the compartments) and put it in closed position - for obvious reasons
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The other opposing area was reserved for the sleeper's attendant so I put one of the seats there, together with a small desk and cabinet.
Now I'm working my way through the 10 seats of this section, a painstaking job. Progress is slow, thanks to real life....
Cheers,
Erik