I don't think this is going to do. I tested it and it takes way too long. A few seconds is the most it may take, so I can run it in a background thread and update the mesh when it's done. And it doesn't even look better than my "triangle-bound vertex mapping" approach. Maybe I could tweak it to look better, but it would never be able to run decently fast at runtime.
I'm thinking there is no alternative to painstakingly prepare each clothing/hair/etc mesh with information about which vertices should morph with the body, and which ones should be "dragged along", maintaining relative positions to their connected neighbor vertices and try to only scale without deforming. But that kind of effort wouldn't be worth it for me. I just wish I knew that code from the Fuse editor...
