Ok, I see. Thank you Mark. I'll have to think twice on how I do this, as firmware upgrade is quite frequent with this unit.

I am now considering using the internal 5GB storage space - currently FAT - originally used as user storage space mmcblk0p9 (even if it says extsd1, it is in fact internal).

I'd have to convert/reformat it in ext3, and then use the script you helped me with. In theory it seems a good plan. 5GB of app space is still pretty good!