Small problem. If the player does not know the saves are being made, how will she/he know to load them?
I don't think hidden saves are a good idea for the reason you mentioned. Accepting the risk of save files being corrupted is asking for trouble. The problem with "idiot proofing" is the inventiveness of the "idiots", so someone somewhere could end up with a large number of corrupted saves which do not appear in the save list.
Open up the load menu and apply eyes to that situation. Pretty sure everyone does this after death.
The point was to conceal the saves being made. If they turn up in the load menu, they can hardly be invisible.
