update! Product link from canvasback: https://www.canvasback.com/rivian-r1s-cargo-cover.html
See below reply for more links as well.
Back in late February, I contacted Canvasback, Inc. to ask them if they had an R1S cargo cover that covered the gaps between the rows when the seats were down...
My LA Silver R1S with cargo crossbars installed.
I just measured the height to the top of the crossbars in standard height and it was 6’3.25” (or 75.25” or 191.135cm). Here is a pic at Standard Height in my small Garage.