Hm... Shouldn't autosave actually be disabled for hard difficulty? Disabling the safety-net?
How about no saves at all? The game is only saved when you exit the game. If your party is defeated after a 3 hours session or the PC crashes too bad...
The variant that was quite comon up to the early 90's (only one savegame that you can save at will, no autosaves) could be easily realized and even forced upon you: disable autosaves, set the number of quicksaves to 1, and start the game with a batch file that deletes everything but quicksave 1 from the savegames folder.
Since the game can easily be modded there is no point in competition and enforcing rules upon all contestants, to prove that you aren't cheating with modded uber-gear, you'd need to record your game, and the 1-2 people that care will see when and how you save your game.
