[Backtobasics]

2 questions:
Where does the EGR return into the intake manifold?
Where the the crank case evacuation system (vent tube, etc) return to the system? I would not expect a PCV on diesel due to lack of vacuum.

These would probably have to return into the suction side of the turbo (I would think).

My concern is the crank case evac and egr dumping sooty air back into the intake or pre turbo, allowing the soot and blowby to blow all over the intake before being re-introduced to the cylinders.

The only way I see to keep it clean would be periodic spray with carb cleaner / intake tract cleaner. Perhaps you could reposition the crank case vent system to introduce into the air box, before the air filter, where the filter could trap the soot before it heads into the intake manifold?