Don't forget you only need to connect to the PC to upload the initial image. Once you've done that (if you're doing something like scriptexecutor) you can use any of the interfaces on your target hardware to get the image from.
For the Slice project, we just took the compute module and put it into the Slice case, then connected power and plugged in a Pi which is running rpiboot -l. This then pushed into the Slice a buildroot (similar to scriptexecutor) which booted, mounted a server nfs drive over ethernet and downloaded the image directly to the eMMC. The Pi only needs to be plugged in for about 15 seconds, the first thing I did was to make the LEDs go all blue so the operator knew to unplug the Pi. At the end of programming, the LEDs would go all green or all red depending on whether it passed or failed. The test log would have been uploaded to the server
Gordon Hollingworth PhD
Raspberry Pi - Director of Software Engineering