That's what rigging the camera to the body rig would do (tested and confirmed with a game I am designing). It limits the camera movements to normal kinematics. Without the ability for the avatar to stand, if the user stood while using the Rift, the camera would stay at the highest point possible according to the rig, and.. well.. the user won't do that again. Unless they have their VR legs, they would get motion sick. It's a trade-off, sure.
You would still need to have a "Reset Rift" option though to deal with IMU / Positional drift :\ Someone really should nerf the Earth's gravity and magnetic poles so it will stop doing that. Oh, as a side note, what happens when the poles go through their reversal and you were in the Rift?