Hi Mark or Ben,
Are you able to include the application "BookSwap" in to PRS+?
It is a file manager to copy and move files between internal memory and SD card but it runs from the SD. It would be nice to integrate it into the options of games& utilites of PRS+.
Here the post
https://www.mobileread.com/forums/showthread.php?t=21636
excuse my boldness.