Roadway Drive thru using LumenRT-masking out existing roadways, traffic signals, etc.

I am preparing a fly thru in LumenRT with the combination of a drone flight processed through ContextCapture as well as a ConceptStation concept.  I combined the files in ORD.  The drone flight was attached as a reality mesh.  I clip masked the existing roads, traffic signals, etc. out of the reality mesh so they did not show up.  This created holes in the existing. Is there a better way to remove the existing features such as roads from the reality mesh so they do not show up without creating holes?  I know there is a way to sculp the new terrain in LumenRT but this is a large ares, so I am looking for a simpler way.  When I brought the drone flight in it was 109 feet higher than the concept, so I moved the z value of the reference file in ORD to make them match.  This created a large difference when trying to sculpt the terrain in LumenRT.

There are areas of existing that we did not do a drone flight.  Anybody have a good source of data to fill in that area besides an image draped on downloaded lidar?

Thank You,

Gerard