They make a mount for sensor that puts it on the front of the headset and the software corrects for headset position. The newer model Leap Motion has 180 degre

They make a mount for sensor that puts it on the front of the headset and the software corrects for headset position. The newer model Leap Motion has 180 degree field of view so essentially - if your hands are in front of you then it can track it. The range only needs to be as long as your arms. Some hand positions are self-occluding but this is a problem less often than you'd expect. Direct sunlight used to be a problem because of IR interference but this might have improved (I haven't tried the it since last October).