Well, the only bolts on the backside of the knuckle are the 3 bolts that hold the hub assembly to the knuckle. As long as the ball joint nut is tight and the joint is full of grease you should be good there.
At this point it may be time to jack it up so both tires clear the ground, and with the pass. side tire removed have someone turn it lock to lock and pinpoint the area that is making the sound.