Found exactly what I was looking for here.
The driver combines a several mount points into the single one
Actually I think this may actually be better then the Drive Extender things…
Played with AuFS a little, and got it working on the laptop.
This is the mount command that worked:
#mount -t aufs -o dirs=/home/outsider:/tmp=ro none /mnt/aufs
Just need to get it working on the server now.