Tail and other debris
Those who imagine the tail separated on impact must realize that the plane would not "sink" but be fragmented into thousands of small pieces, with a massive region of floating paper, insulation, and all manner of debris, intermixed with fuel, oil, and hydraulic fluid, some of which would be deposited on the surface of the tail section - we know this looks clean as a whistle and was found off by itself - making it almost certain that the tail separated well above the main wreckage site.
I would then propose an alternate theory - from the visible damage to the tail section's lower region - the presence of middle and rear mounting boxes that have been torn from the empennage structure - perhaps the front mounting lug failed, allowing aerodynamic forces to lever the tail backward just enough to allow 500+ MPH air to penetrate into the body of the tail section - this would probably be enough to pry the tail section from the empennage and cause the visible damage to the lower part of the rudder, and would also result in the obvious torqueing seen on middle and rear the mounting boxes that remained attached to the tail section. The front mounting lug is missing in just the same way seen on AA587. This would also explain why the rudder remained attached to the tail section with no evidence of excessive sideways force being applied to it.
-drl