Not knowing what the smoker looks like, how tall it is, or what it is made of ---I'll take a shot.
The hanger you show seems to be long and not knowing how big your pork belly is, you need to take into account how low the meat would hang if you put a rod in & then hung the hook. On a smaller smoker this could take up a good % of the space.
I would get a stainless steel hook similar to the one in the picture below.
But I would look for one that has more of a bolt end then a screw end. In the top of the smoker, drill a hole the same size as the bolt hook. Then put the bolt hook through with a washer both on the inside and the outside. Use a nut on the outside to tighten the hook in place.
I would then take your hanger and cut off the top hook where the red line is in the picture. I would leave the "loop" on top of the hangers. See picture.
Hang your meat on the hanger then put the hanger on the hook you installed. (hang it by the loop.)
What this design does--puts a minimum size hole on top. If you want to smoke something without using the hanger, you can remove it and plug the hole with a washer and a minimum length nut and bolt.
It takes less space so you have more space to hang meat.
The one thing is when you hang the meat you have to make sure it is centered on the hangers so it hangs evenly.
Well, that's my idea