i dont see how this would work... the save files aren't archives and as far as I know the game isn't going to read zip/7z/etc. files with saves in them...
Before I start a new toone. I rename the save file. From save to BckUpSave_"name of the toone". then I compress it with 7-zip to "Add to BckUpSave_"name of the toone".7z"
Then I open the old save file and delete all but a few saves. At anytime I can un-zip the old saves. Extract to BckUpSaves_"name of the Toone"\. This will add a file with all the old saves. Can dig through this and add any of the old saves to the current save file and play the old save. When done with the new file created from 7-zip. You can just delete it. Takes about 10min to create a zip file of 3 gig to 300megs. Only takes 5 secs to replace 3 gig of saves from a 7-zip archive.