I've been hanging by my balls, literally, for about 30 seconds a day since Wednesday. I can hang with one hand on my balls and the rope above for about a minute; or with my legs pushing against the wall.
The stretching is hard on my ball sac; it sometimes causes the skin to become chafed by the friction of the rope, so it roughens a bit. However, you must persevere and it gradually becomes tougher and can take 9 stone!
By the way, my balls still contract and shrivel when they are cold. It is only when they are warm and loose that they hang really low.
Just being honest...