The idea is to shoot, in turn, both sides of the image, so that when developed it would be possible to slit the film longitudinally and 'restore' the lost half with black leader, as the characters would've been reacting to the presence of the wall that this absence of light would infer to the viewer.
The idea of doing it either digitally or in the print is a no go, we're using splicers and steenbecks etc for the edit.
It does seem unfeasibly difficult to me, the chances of it just being completely eaten by the projector seem so high it may not be worth it.