On my headless NAS I have sdf1 (a flash-card) mounted as / while /home is mounted from lv00 (an LVM volume backed by a software RAID). To be able to access the machine when the RAID fails, I have a copy of my ssh public key, etc. in /home/foo/.ssh on the file-system from sdf1.
To update the files that are hidden by the mounted /home I normally remount lv00 in /mnt/home, do what I have to do, and then move lv00 back in place.
Is there a way to achieve this without unmounting /home?