Consider the situation.
Middle of no where Arizona, no radar trace, no data recording, no ELT installed, no witnesses, no survivors.
Add in post crash fire.
As to the length of the debris field....lots of light weight parts being shed....strong winds....not all that amazing it would be as long as it is.
The 225 crash had two main parts....Rotor Head and associated bits...and the airframe.
One thing is certain...the Rotor Blades hit the airframe and the aircraft disintegrated into lots of pieces.
The Investigators worked with what they had.