Tiger-
One idea is to try two clamps - one at the front and one at the back of the Wench. Try varying the tightness of both clamps - they don’t have to have the same amount of grip. Also, try varying the distance of the two clamps.
Some guys have used this added clamp to break the 15-20lbs range with the Wench.
Another idea is to tighten your clamp snug and then while holding the Wench loop out away from your pelvis allow your unit to stretch out a bit, wait a few moments, and then give the clamp another click (or a few more, whatever gets it perfectly tightened down) - remember to do this subsequent tightening while giving your unit a mild stretch.
Varying the amount of wrap you use can also help achieve a better hold. Sometimes less is more, and sometimes more is more - it is very much a personal preference, as is what type of material you wrap with. This can have a great impact on comfort as well as function.
SS-
I think Itsgotime hit that one perfectly.