Setting Vive ipd without using hmd knobs

In a SteamVR project, I need to use two cameras in which one camera renders to the left eye and one renders to the right eye. Along with this I also need to add my own ipd without using the knobs on the Vive headset. I’d like to add an offset to both of the cameras transforms from a center SteamVR_TrackedObject to achieve this. The problem is that by default, every Unity camera in an OpenVR project automatically tracks to the HMD. Is there a way to stop cameras to from doing this? If not, I’d also be interested in another method to adding a custom ipd (without using the Vive knob) to a two cameras setup in an OpenVR project.

@ZenUnity did you ever figure this out?