I think it's worth mentioning that I travelled without my laptop for this holiday getaway. Instead, once I was back at the cottage, I used the SD connector kit for my iPad Pro, and imported about a dozen images to work on - in RAW - directly within Lightroom Mobile on my iPad Pro. This gave me the added benefit of being able to post high-quality images to Instagram, Twitter and Facebook, without having to lug around my laptop. Once I got home, I imported the rest of the images through Lightroom Desktop, and changed the physical location of my synced photos from the weekend, to the new permanent folder on my external drive.
That last set of steps was the least intuitive for me, admittedly. Maybe because I don't do it often enough. I honestly don't know how the LR engineers can improve on the process, but locating the images that were synced down from my iPad, and making sure I not only relocated the files, but ALSO the XMP data, was frankly not the most seamless experience. Sure, you can move the photos easily enough right from within LR. But moving them does NOT move the XMP data. So, for a panicky few seconds, all my images had lost their processed look. I ended up having to go into the Finder and move the XMP files manually (ugh).
In hindsight, I think the issue is that I did not move the folder itself - just the contents of the folder, and in Lightroom Folder panel, you can only see folders and images, not the sidecar files.