It is best to keep the hospital or QT tank simple. No substrate or LR. You could use dead rock, or just PVC pipes. Fish must have comfort zones to hid in. No lighting is necessary unless the tank is in an extremely dark room where fish will be in the dark wo lighting.
One very important think to do is to paint the bottom of your aquarium [FROM THE OUTSIDE] with black paint. This will prevent fish stress from the reflections generated off a bare-bottom tank.