Have you tried different types of litter? Different types of litter boxes? My cats are pretty accepting of different types of boxes & litter, but I've convinced them to only poop in the bedroom box if the door is closed by using a litter they like less in that box. The typical recommendation for litter box troubles is to offer a box that has low sides, is very spacious, not tucked into a corner or cubby, and a fine grained, unscented litter. Clay litter is what my foster program usually recommends for litter box avoidance.

If his poops smell that bad, changing his food might help. I have a litter box right next to my couch, and my residents also don't really bury their poops, but I rarely notice the poop smell unless I have fosters with intestinal parasites using that box.