AR plugin operating at native camera resolution

we are looking to build an iOS/android app with augmented reality. there are many possibilities with varying levels of support, price, etc. one answer we could not find is:

is there a Unity plugin that will allow to render 1 frame of augmented content at the native camera resolution and export the texture as a "photo" to the camera's photoroll?

the goal is to store a full resolution photo of the augmented scene (not simply the screen resolution). the idea would be:

• augmented reality is rendered over a detected marker

• user presses shutter button

• realtime render and AR analysis is paused

• full resolution image (perhaps 3,264 x 2,448) is taken

• rendering engine is adapted to full resolution of camera

• the scene (camera image + overlays) is rendered-to-texture at the full resolution

• texture is copied and saved to disk

• rendering engine goes back to screen resolution

• realtime render and AR analysis resumes

of course a "hiccup" is expected, but the image would not need to be AR-analyzed; the analysis result and mapping from the previous frame would do just fine. i guess this could even happen without the plugin knowing about it, but it means the camera can be quickly offloaded from the AR plugin, utilized by another means allowing the full resolution capture, and reloaded, whilst taking less than, say, 2 or 3 seconds on an iPhone4S.

a scan of the vuforia and in2ar docs/forums, as well as unity forums did not yield a clear answer. (this thread raises the issue, but answers are inconclusive http://forum.unity3d.com/threads/159450-Unity-4-Vuforia-iOS-camera-resolution-problem).

thanks for any ideas/pointers, alex.