I've been running single camera mostly, I have 2 Rifts, and could use the camera from the other one if it wasn't in use, for room scale, but I haven't even bothered trying that yet, as the only room scale game I play was Vive only until recently. Pretty incredible how good both Rift and Vive work on a single camera/sensor, when sitting the Vive will work with just one of cams picking up, I know this as I had a ceiling fan blocking the far corner camera line of sight to my desk, and it would still work while seated when the #2 Vive camera was unable to track the headset properly.
I didn't realize the touch controllers for the Rift came with another camera, I wasn't going to bother with them, maybe I'll give them a whirl now.