I have considered using CEF as well (via cefpython), but the main deal breaker was that it isn't packaged anywhere - so I'd need to ship my own copy of it with qutebrowser, which is usually not something you can do with Linux distribution packages.
You definitely can. I do: https://cretz.github.io/doogie/. Prebuilt versions are available at http://opensource.spotify.com/cefbuilds/index.html. In fact, I'd say shipping with the browser is ideal for a few reasons. It's not a lib that should be shared across the system IMO.
Could you elaborate why you'd prefer shipping it with the browser rather than sharing it?