I forgot to update on my proactive recall regarding this. The ranger was coming to replace my 3rd charge port door, which he didn't end up doing because he had the wrong part. I had some other issues which were closed because they were firmware related. But the service also booked in the harness check.
He had a look and said the harness didn't need replacing, which is great because I have an aftermarket power tailgate and it would have complicated things. He did say that he would have been happy to remove any unfamiliar cabling but wouldn't refit them for obvious reasons.
Here's what the 'minor' fix looks like:
View attachment 858059
The check was done without removing the plastic panel on the tailgate, so if the minor fix is needed it looks like a straightforward job.