Honestly I hadn't initially set out to create a document--rather, I had been putting together notes in Joplin while figuring out the process for myself. I have been trying to get into the habit of documenting how I set things up when I am doing something new or different. For certain things, I have found good documentation can be more valuable than a backup.
At some point, I ended up referring to the notes for a solution here in the forum (this one), and someone on the team mentioned it might be handy if I could write up a guide and put it in the wiki. The wiki post was honestly a piece of cake to write, because I just added some explanatory sentences to the notes I already had.
When we started getting close to the Raptor release, I thought it would be fun (and/or funny) to install every Raptor spin with this method, and I decided to write a topic to accompany the wiki post. That is when I had to put some effort into it, because multibooting so many installations without using the rEFInd Boot Manager would be...well, less awesome. 
So I had to double-back and put together some notes for how to get rEFInd set up. As you can see, those notes ended up being more lengthy than all the subvolume setup! 
In the end, it did end up taking a while to put together--at least a few hours. And although the whole project was done somewhat tongue-in-cheek (I have turned something practical or useful into a novelty, or even an absurdity), I do hope it can be a useful reference for folks who would like to get started using rEFInd or multibooting with subvolumes.