There are photos of Sam Kiszka (GVF bass player) and a 2000S in the Sept. 2018 issue of Vintage Guitar.
Here's that photo;
It's the same one with two Sunn logos from their sessions at Blackbird in Nashville in Feb '18, five months before the Tonight show performance. I'd guess he brought that old Sunn with him. No mention of how the bass was recorded for the session, however it would seem to be logical that you don't drag a 40+ year old tube amp into a studio and NOT mic it up to record tracks.
The article also mentions that Sam also puts Jazz necks on his P's, as I do with my P's. Maybe we're kindred spirits...
A vintage 2000S would be a very unique piece of gear for a rental company back line, I wonder if I could sell one of my 2000S's to a rental company for top $$$?