Update time with bad news and good news.
The bad news is that I don't have a solution for a Canyon CF SLX. The good news is that I have a solution for the Merlin Works CR/Mavic Cosmic SLS (and possibly older mavic wheels more generically). It looks like everyone is going to end up with their own custom config with your worst case being the possibility of having to switch out your wheels or do something scary to your deraileur.
Before I dive in your experience may vary widely--I've got a buddy who took his Scott Addict with custom bikehubstore.com wheels and milled out the back of his Ultegra cassette and jammed it on a 10sp body, essentially moving everything CLOSER to the hub. Meanwhile on the opposite end I needed to move it AWAY from the hub using a new freehub body described below.
Lastly, Mavic seemed surprisingly unknowledgeable about the issue, despite countless wheels going through the 10sp -> 11sp transition. FWIW they did offer to 're-dish' my wheel if it came to that. I don't know much about the process but given that I've got about 5mm between my 23mm tires and my frame, I'm glad to not need that.
So, for older mavic wheels it all boils down to the freehub body.
Details are scarce and there is a lot of documentation that suggests that you can take a 10sp freehub body, remove the spacers that come with it, slap on a 11sp cassette and you're off and running, but that was definitely not the case for me.
Looking at the OUTSIDE newer 11sp freehub body next to the older 10/11sp freehub body you wonder how on earth the 11sp is going to fix the spacing problem (they are all but identical), but if you look INSIDE the newer 11sp freehub bodies have an extra washer which effectively pushes the entire thing out and away from your hub. This made all the difference:
Could it be that simple?! It appears so:
Just as confirmation, the cassette body is exactly the same size on the outside so that lil 11 tooth cog isn't getting pushed out or anything:
Out of an abundance of caution, and because I didn't believe the freehub body would fix the problem I picked up a SRAM chain catcher. It's like a dream catcher, except for chainrings:
So hopefully that helps some Mavic people. Good luck to everyone else! I'm going to stay subscribed to this thread to see how things continue to shake out.