Yes, I think the best bet would be focusing solely on the PLC module. The CCS socket will be unique to the end user because Europe and North America use a different socket, and some people might already have the contactors (e.g., from a previous CHAdeMO conversion). Worst case, people buy the parts they need to complete the system separately, or we could set up a group buy for Tycos, sockets, cables, etc. if it makes sense.
I might pick up a spare Chevy Bolt EV Power Line Communication module for about $150 just to look at it and see how it works and is put together. It might only speak the DIN SPEC 70121 standard, though, which could be limiting.