Thanks everyone.
I just ordered myself a Echo93 V1
That looks like it will do the trick. I watched the video on the QD side-mount version but I really preferred my sling mount point to be the rear of the receiver instead of on either side. I'm sure you can train around it, but for me, if my Sling was on the outboard side of the rifle I'd be getting all hung up on it every time I needed to shoulder the rifle or switch shoulders. I'm sure it can be done just fine, but for me, I'd most likely make a mess out of it.
However, after visiting his site and looking around I found that V1 attachment. I'm a little bit concerned that it won't work with the reinforcement plate above the grip on my SLR-104 but after some googling I did read about some folks that it worked fine for. I'm also a tad concerned that the angle it comes downwards at might get in my way, but most of the reviews I read seem to say thats not a problem.
Either way, it looks like it will work perfect with an extra Magpul MS2 Sling I have sitting around in a box that isn't being used for anything.
Thanks!