I think you actually can do that with the game as it currently is. The only tfs likely to occur without your intervention are BE Rhianna, Soldier Akarion, Spy Marazet and Princess Richter, which can all be prevented. You can prevent the first two by beating Akarion in the first challenge; prevent Spy Marazet by losing the chess game to her; and prevent Princess Richter by offering to hide him during that event.