https://github.com/mpartel/bindfs
FUSER filesystem similar to mount --bind, but allows you to mess with ownership and permissions.
Useful command:
sudo bindfs -u a -g a --create-for-user=b --create-for-group=b from to
Mounts from/ on to/.
b must exist.
-u a -g a: everything seen on to is owned by a:a
Everything created / saved on b, is created on a with owner b:b.
Unmount:
fusermount -u /home/johnc/ISO-images