Setting Visibility of ArcGIS Elevation Source and/…

I have the ability to hide/reveal all kinds of Layers with Input Events (Tile, Vector, 3D, etc). 
I also figured out how to use Mesh Modification to hide/reveal specific areas of the map layers. This is very handy.

But I cannot control the rendering or visibility of my Elevation Sources. I’m trying to make an Image Layer 0.3 opacity, so that you can see downward through the layer into the subterranean areas which is full of spawned mesh actors. But the Elevation Source prevents transparency. Disabling it disables the elevation of course, and there seems to be no kind of ‘Set Is Visible’ node for it.

Any ideas? I’m using BPs in 5.2