I have an assembly of components I need to create a split cover for.  My intention is to house the assembly between two plastic parts that pick up the geometry of the internal components for mechanical mounting.  I have explored using molding tools however because the assembled components do not make up a nice solid body (or surface bodies) after saving as a part file, this method very intensive because of all the additional work to close up gaps and so forth.

I have also tried doing the tedious method of creating each part separate with a ton of extruded boss/bases and so forth.  I don't like this because editing down the line becomes a nightmare if any of the assembly components internal to the cover changes during the design phase.

Has anyone experienced this and found a nice way of creating a split cover for an assembly?