there's more info on the reddit wiki
https://www.reddit.com/r/oculus/wiki/touch_360_roomscale
Quite a few people play like this and reports generally suggest a good 2 sensor set-up is almost as good as a 3 sensor setup, but there is a tiny bit of occlusion where neither sensor can see your hands. For the headset itself it should be near perfect.
I've got 3 sensors, one on my desk to the right of the monitor, pointing slightly up (it's a corner desk), one mounted behind to the right near the ceiling and one mounted to the left near the ceiling and even though the sensors are not in the technically ideal locations it's still been flawless for me - except that I have a big mirror which is in sight of one sensor when I'm sitting in front of the computer. occasionally it goes crazy and puts me about 5 metres outside of my guardian bounds. I've fixed that by cutting up an actimel pot and blu-tacking it to the sensor so that it covers the mirror from the sensor's view.