It fits! It moves! It drinks coffee!!! (ah oops no that's me).
It's far from perfect, but I can say I'm finally getting the hang of it. The pictures above are the same mesh, fitted to the avatar (default size and large). And a bit of poke-through.
The one thing that took a while to click was how the normal bones interacted with the collision bones. You'd think weighing entirely on the collision bones would work. Nope. Sometimes you want the vertex to move with the skeleton, but you don't want it to shrink / grow as much as it would if you assign it all to the collision bone - that's where the old classic bones come to the rescue. They move, but they don't swell! Good old bones!!!