Any way to get VRSettings.showDeviceView to render into a Render Texture?

Full screen mirroring is cool and all, but it's not very useful if I want to show it in a window, or some split screen UI, or anything else.

So the way I have things set up now is to set showDeviceView to false, and created a camera with a render texture attached in order to do a split screen UI.

Unfortunately, when I use a profiler, I see that this gobbles up valuable CPU time. Attached is a screenshot of the profiler showing Camera.Render.Drawing using a pretty nasty mesh where the FPS...

Any way to get VRSettings.showDeviceView to render into a Render Texture?