Although this is not the right place for this discusion: it has been done before.
Years ago there was a scanning back for 4x5 inch, unfortunately you don't hear about it anymore.
I would give it a try with a 8x10 inch LF setup and seen what comes out of it.
You might have to adjust your focus a bit, because the scanning part will not be in the same place as your GG.
For landscapes and architecture you could come up with >200Mpix shots cheaply, providing you have the propper gear (camera + lens) allready.

Mind you, some scanners need a special light source if you want to scan negatives/slides this way, but what the hell, give it a try !

Peter

Peter