Hi @JColvin,
I was able to build the new .xsa in Vivado and import it into Vitis after a bunch of global search and replace in the Vivado and Vitis directories to get rid of the E: references.
The crucial part was I extracted the Vitis sw.ide.zip file, did a search and replace on the E:UpgradeProjects string, and the rezipped the directory. After that I had to change the path to the lscript.ld file.
It took a few tries, but the demo is running on the board now.