Hi Hedge, I'm trying a similar thing but having some issues getting Sierra to "see" the egpu. I'm slightly different in that I'm running off the Touch bar MacBook Pro. Currently I have the card hooked up to an akitio thunder 2 through an apple thunderbolt 3 to 2 adapter. For whatever reason, I still cannot get the card to show up in about this Mac. It's like the OS doesn't see it. I followed your plistbuddy suggestions. Still no luck. I feel like I may be missing a step.
After having no luck with plist buddy, I tried modding the automate-eGPU script as per your suggestion. when I run that it finds the thunder 2 but says no eGPU found. is it possible this is a bad card? I have used the thunder with a few other computers and a few other cards but just seem to be having a really tough time with this one. I have confirmed SIP is disabled,