I have run into a bump in the road though... I have the mr2040 model (with battery). Unfortunately I can't use the same firmware that you used for the mr2030. The firmware I used is larger than the other version so it does not leave me sufficient room to load all of the various USB storage drivers.
I thought that I had managed to squeak by but when I try to mount the drive, I get a 'failed: Invalid argument' message. I'm just doing a simple 'mount /dev/sda1 /mnt/usb/' command. sda1 is visible in /dev so I believe that the drivers are working to some extent.
I did not load the kmod-usb-storage-extras driver. Perhaps that is necessary after all?
Looking forward to future videos on this topic! Please keep them coming. Perhaps discover a way to upgrade/change out busybox with a more functional version?