I agree with Wullie! You don't have to have a rear view mirror, I drive a transit that doesn't have one, but you do have to have wing mirrors, unless your vehicle was designed without them! You are allowed 1m of rear overhang I believe BEFORE you have to put a warning flag on it, With a flag you are allowed a longer overhang, but I do not believe you are allowed to have anything sticking out the side of your vehicle more than a few inches as it causes a danger to pedestriansm, or yourself if you have an accident.
Matt