Is this feasible?

I have a device in a vehicle that is normally updated by inserting a USB memory stick into the device then selecting the required file using the device which then installs the file. I am hoping to set up a BBB with a GRPS/GPS Cape so that I can SSH to the unit and when required, send files to it using SCP. What I want to do then is to serve the files up to the other device as if the BBB was a USB. If I had a USB cable running from the USB port of the Pi to the USB port of the Device, could I mount the USB port and copy the file(s) to the directory linked to the USB port? I am trying to serve the files up to the device in lieu of manually using a USB stick.

Any help or guidance would be much appreciated.