Checked the system settings for ten different laptops at the shop and could simply adjust all of them to stay powered on with the lids closed. Did Windows, Mac and Linux machines. No problems. So since they can stay on then you can definitely monitor them via a switch that let's you toggle between connected devices and can just stack them without a shelf. Only caveat is you have to be able to log onto the devices to do so. You may be able to adjust it in BIOS too but it wasn't obvious to me how.