i always think to myself
someone should start an official "cab in a closet" thread and i have yet to do it. Basically you need to create an environment (cabinet grow room) inside an environment (a closet). I too live in a rented apartment and
i need to be very discreet.
as you can see my closet doors are vented at the top and are made out of aluminum.
the cab is small enough to fit in the closet comfortably and heat is suck'd from through the cool tube out the box into a soon-to-be carbon scrubber.
just make sure you light proof the fuck out the cabinet and get cabinet locks you shall have no worries. i just built a false wall and homemade door w/ hinges and magnets behind those sliding doors. Weather stripping and caulk are your best friends when it comes to light leakage.
My suggestions for you in an apartment is to not make any noticeable modifications to the construction of your apartment. Thats some hot shit and we dont need that!