Milling with long tools - maximum Z height below part top

[kwgochenaur]

I have a part to mill that exceeds the Z travel of our router. My intended solution was to machine it in two stages, first with a 3" ball end mill, then a 6" ball end mill. For each stage, I plan to use a 3D Adaptive clearing, followed by a 3D Contour. Programming the first stage is no problem, just raise the bottom to the desired level. I'm currently working on the 3D adaptive with the longer tool. I can set the top height so it only machines from the desired level down, but I can't bring the retract and clearance heights below the part top. I could reduce the retract in the Gcode, but I would also have to add a point away from the part so the travel move doesn't pass through the part. Splitting the model leaves me in the same place; lots of manual editing to steer the linking moves away from the part.

Is there a better way to rough the part?

Thanks!

-Kyle