In the df output you attached there is no sd card mounted.

An example:

If you undo your modifications, after reboot, your sdcard gets mounted to
/run/user/100000/media/sdcard .

Afterwards, just run:
Are there any problems with the above (except that it is not automated)?


To automate it all you have to do is to ensure it is done _after_ mounting the SD card. That means that either you edit the mount-sd.sh script or insert a new udev event handler.