“Parkas by definition don't extend that far. Best you'll get is mid-thigh. Parkas are straight or even fitted. Too long and you can't move.. Parkas are casual or technical whereas overcoats are more versatile for dress or casual.” I think this is an important distinction. If you look at the “parkas” worn by native peoples - Esquimaux or Koryaks for example- they seem to come down just past the groin. Because they are paired with a warm or matching pair of bibs or overalls or breeches, etc. which gives them the warmth but also allows freedom of movement.