Correct first person view for full body VR with MoCap

Hi there,

i'm currently trying to build a setup for full body VR, based on Optitrack Motion Capture, Oculus Rift HMD and Unity3D. 
Now there are two diffrent ways to get the position of the Oculus. First one is to place markers on the headset and track it via Motion Capture. Second way is to place a camera on eye level of the avatar in Unity.
The first method takes a lot of time for preparing, so I thought the second method would be quite easy and reliable.
Main problem with it now is the perspective view. I've tried it with the Oculus Camera Rig in diffrent settings (per-eye camera / one camera). The view is show incorrect, either its far from the avatars face or inside its head. Head rotation seems to make trouble too. When I turn my head, the camera is turning more than it should, so far that I can see the avatars ear.

Does somebody have an Idea to get the correct settings or is it more common to use the seperate tracking method?
Maybe disabling the Headsets position tracking would make it, because the camera should use the heads movement instead of being semi-fixed to the head. Didn't find a way to disable it yet.

Looking forward to your answers.