Another thing that I do is start each hanging set (about 20 mins) with about 3 pounds. I then add 2-3 pound after about 1-2 minutes with that weight. So then just work up to the weight goal planned. Slow start with a gradual weight loading. You can feel your penis adjusting to the load. Stress at first, but then some sort of relaxation.
This helps with keeping the hanger in place, but it also gets more fatigue for me than just going to the max weight.
Some other threads have suggested that gradual loading as a way to minimize the penis protective reaction to a heavy load. I think they are right.