I added the final element last night: the KeyStep and JV-1010 set to a slow string patch. The JV-1010's diminutive size makes it perfect for this application.
Everything is starting to sound suitably atmospheric and dark now lol. I will need to add some processing to the strings, which will be the final step towards getting this done; probably some phase shifter/flange and a good dose of Space Echo.

My plan now is to get the RV-500, Blackhole, and whatever effects I use for the JV-1010 onto one of my Pedal Train boards and get that down on to the floor and off the shelf, as it's not really needed there. That should free up some valuable real estate...