Thank you for your detailed answer.
Let me write down my plans more specific:
Power: 18650 battery pack (serial/parallel) with buck converter.
HDD: 256 GB SSD
Multi I/O USB 3 Card reader (Kingston is my favorite)
SOC: Needs Stand Alone Sata interface + USB3 -> Espressobin
Display: I2E or SPI for displaying status. High speed voltage converters if needed with the GPIO pins of the EspressoBin
Buttons: U/D/L/R Enter for menu options.
3D printed Case.
Being on photo assignment I need a fast method to dump the contents of my memory cards to disk, so that I have a second backup.
The cards are all 32Gb or 64 GB so USB2 is too slow. Knowing that I also need to know if the EspressoBin USB3 and Sata controller are separate or bridged.
I’ve found Linux software on Github that does the job (includes a 2.2″ I2E display)
I’m going to test this on mu OrangePI and /or Raspberri Pi. If this works I would consider ordering an Espressobin, because it’s the only board I know with Sata and USB3.