Yep, I have 3 sensors as well. Mine are all mounted on the walls near the ceiling. I have one above the left side of my desk, one directly to my right, and one behind me. This allows them all to have good sight-lines over the monitors, and I can stand up and move around without it losing tracking. The only time I lose tracking and the orientation gets messed up, is if I take the HMD off and put it in my lap, or something along those lines. (In my lap, it's below the desk level, and I'm between it and the rear sensor, so all three lose line of sight).
For the right-side and rear sensors, I had to use extensions cables. I think I had bought 10' (3m) cables, that are not the "active" cables that Oculus recommends, but they worked fine. Any longer than that, and you probably would want "active" cables (they draw a little power and self-amplify).