I'm in the same situation atm. Mine is relatively stealthy, big wooden cabinet with a table cloth over it and a chair pulled up to it. People look at it and think it's just a desk of some sort. Additionally, the doors to the cabinet have big locks on them. If maintenance does come in, doubt they'd rip the doors off to see what is in there. The most they'd see is an exhaust pipe if they looked behind it.
Just make sure it isn't near anywhere they'd ever have to go. (Water heater, CO2 detectors, Smoke Alarm, Electrical Breakers; They come in to replace the batteries and do regular maintenance.)