As these guys said, it's pretty much unavoidable with compression hanging. As long as you keep your sets <20 minutes and ensure that you're not completely cutting off circulation you should be fine.
You can do a simple test to see if your glans are still getting blood flow. While hanging, firmly press into your glans with a thumb or fingertip for a few seconds. When you remove your finger, you should see a very pale area that quickly returns back to color as fresh blood fills back in. This can let you know that bloodflow isn't completely cut off
Have you considered vacuum hanging? While not capable of the same kind of weight, it's much more comfortable and your sets aren't limited to 20 minutes