hi there,
I have similar thing going on, i put the originals(your .tiff) in a folder like “raw”(your fullsize) and in tonfotos -> folder viewer you can rightclick the “raw” folder, then click on this “stop indexing for this folder” button. then tonfots does not show it anymore at all.
and the scanned pictures i just have in “scanned” folder which will be seen in tonfots normaly
maybe this helps :D