You can pick up one of the "side mount" sling swivels from several places, like Tapco, Delta Force, Cheaper than Dirt, etc... They usually run around $10, and clamp to the barrel/tube. Then, what I did was to saw off the sling attachment part, drill through the base part, and presto, instant "uncle mike's detachable". That way, you've got the provision for a sling, that WON'T be on the gun while it's serving as HD.
FWIW, I also own the Winchester defender. It has the smoothest action I've ever worked. The only thing I like about the Mossburg is the safety. I'm a leftie, and don't like needing two hands to click the safety "OFF". Mine didn't come with the Tru-Glo site on front, but I'm going to stick one on there one of these days.
I tried extras like a Choate pistol grip & stock, but I finally put the original back on and stuck all the other stuff in the closet. The Pachmayr pistol grip is nice, if you REALLY want a small but not so easy to point SG. It definitely handles the recoil better than any of the others.