Combining peak design 4L outdoor sling with small camera cube?

I have no experience with peak design gear, but came across this brand while looking for a camera bag that does not scream "camera gear". I know that the sling bag by itself does not protect the camera from drops I was wondering if anyone has combined the 4L sling with the small camera cube? I know people have done it with the 7L sling, it's even marketed with that option as far as I know, my issue is that the 7L is a little bit to big for my everyday use.