I pose that, limiting the locations where the player may save, would greatly limit save scumming in general. Perhaps not anywhere in a dungeon, perhaps simply not in a dungeon - regardless, I believe that being able to save whenever and wherever causes gameplay to suffer. The value of randomness and risk is negated and the player is encouraged to deny his own choices (and, therefore, become strangely selective of what constitutes a 'fair' game or not).
But of course, that causes another issue. What if someone happens and you've got to stop playing the game? Well, for that I suggest a secon