Well first off I would like to state that my theory may be false but I think it is correct.
It would be impossible for the makers of your extender to come up with an exact figure on how much tension the penis absorbs at each level. Larger penis’ should feel less tension at lower levels than a smaller one would. That being said, your comparison of hanging to extenders is not accurate.
I have never tried hanging so I am not sure exactly what it would feel like. I do know what it feels like to wear an extender for long periods of time at maximum stretched levels. It is not pleasant. You will feel extreme discomfort from this, and I only imagine that the discomfort would be worse with hanging.
If you are going to wear an extender for up to 8 hours per day your main resposibilities should look something like this:
- Condition your penis by working up to the 8 hours per day (start fairly low)
- Wear the extender at a low level. I read that you should start around 4-5cm below your BPEL.
- Keep your penis warm the whole time. You will have to have lots of time in between those 8 hours to heat your penis with jelqs, heat pad, etc..
Make sure your penis does not go cold
- Pay much attention to your penis the whole time it is extended
This to me does not sound like it should be recommended to anybody unless they have a lot of experience with PE and extenders. Also, if wearing an extender for 8 hours a day requires this much attention think of what hanging requires. Not only is the force greater but you would have to wrap and unwrap yourself 100 times a day. It is not practical at all.
Your question was “Is it safe to hang for 8 hours a day?”. So I would assume that it is not. If it is it would be very, very inconvenient. I am thinking you meant to ask a different question but I am not sure. So hopefully I have been able to answer your questions or helped you to figure it out yourself. By the way, if you have inexperience with hanging or extending do not attempt either for 8 hours per day. It will most likely only lead to injury.
Hope this helped.