Alternative GTA 3 plot: Claude got rid of his criminal companion to actually let go of the past and forget about revenge. He is now driving the taxi cab, ambulance and taking side jobs to make a living (ignore missions with killing and anything else like that)
Doing this without a pistol and elaborate setup: Flip the Kuruma over using the angled walls of the bridge. Jump into the Enforcer to trigger Claudes stumble back animation as the fade occurs. Saving in Portland: Use a ghost car to clip through the safehouse wall, when you exit the car, you're able to save the game. Once you save, the door will be open.