I thought of this earlier for those who run Midwest Industry rails. I currently have the non-free float model so I don't know if they will work with the free float rails.
Since I am using a CAA stock check weld I had no need for the sling mount that was attached to the butstock. So I removed it.

The MI rails have a front end cap with three cut outs L/R and center.

I then attached the mount to the left side, putting the screw through from the rear of the cap with a nylon washer behind the screw.

Here is what it looks like from the rear

With the sling attached.