Right, I know it's what Xijia was talking about. It just wasn't working, and I wondered if that story was the reason. (Pain in the butt to get the UUID of an inventory folder, by the way.) I am able to get the URL to run by right clicking and selecting 'run this command', which is nice.
Having to click a link to change outfits isn't ideal, but it's a good start.
Also, I'll definitely have a look at RLV. It sounds like it adds exactly what I need.