Great suggestions! With the first example, I failed to trim about 10% of the surfaces.
I finally succeeded with a simpler case: the source solid is a tetrahedron, and the path curvature is smoother.
The trim tool ultimately worked better than the boolean merge, so I might go back and try that on the first example.

the resulting solid:


overlayed with arrray:


the tetrahedron "engraving" into a substrate: