Good point... stupid of me but I didn't think about the input side of things. Could be handled with a tar dump dd-ed straight to the USB device. (That's probably not happening, but it's good to think about these things.)
Or a virtual throw away machine just for mounting a USB filesystem, extracting the files, place them in some dump directory and then the whole virtual machine is wiped.
Heck, the virtual machine for copying should run BSD. :)
