Is there a way by using something (e.g. shp2vec) of generating an exclude for photo scenery in a lower priority layer?  I would prefer getting whatever non-photo scenery is below that (which I will then embellish).

Why not just get rid of the photoreal?

Nope.

 

As far as I am aware you cannot exclude photoreal scenery. You can only overwrite it with new photoreal scenery.

 

Excludes are vectors and really only work on other vector scenery (ie roads, airport boundaries, water polygons, streams etc)

 

If there was anything worth trying it would be an Airport Boundary with Flatten + MaskClassMap + ExcludeAutogen although I would be surprised if it did work on PR.

 

Of course, if the PR scenery is something you made yourself then you can just put a hole in your Blend tiff.