Complex contour features.

Greetings All,

Having a difficult time adding fillets and variable radii to this model. The fillet around the back can be from R.375 - R.5"  The variable contour reflects the guide curves drawn in sketch 4.  Nothing I have tried so far is accomplishing this goal.  Sent is the model and a pic of the finished contour for reference.

Thx lots all.

SolidworksParts And Features