Render Android device camera from native pointer

Using a custom Android plugin and Unity 5.2, it appears to be impossible to use Texture2D.UpdateExternalTexture to set a texture to the native pointer of the device camera's target texture, or Texture.GetNativeTexturePtr to retrieve the native pointer of a Unity-managed texture, and then set the device camera to render to that texture pointer.

This appears to be a bug; in both cases, the texture will change to white. Any assistance or alternative methods are appreciated. My goal is to enable both Unity and Java to manage the device camera; Unity's WebCamTexture doesn't provide a method to access the Java hardware.Camera object, which I need access to.

Has anyone else encountered this problem? Any known solutions?