Quote Originally Posted by AlexGard View Post
Maybe modifying or replacing the dark slide is another option.
Perhaps an addition to the front of the holder to move the dark slide forward a bit. That would thicken the holder and necessitate relocating the ground glass again. A big advantage to a custom back is you wouldn't have to modify the camera or a holder, so you preserve the option to shoot 12x20 film/dry plates/paper negatives in the future. Also, most custom backs will accomodate a variety of plate sizes, so you could have it built to take 12x20, 8x20, 12x16...

And yeah, it's tough waiting for a new camera, especially something as epic as a 12x20.