I do not hang (as yet) but have got blisters from using a VACextender and from pumping. Usually happened after pushing the envelope.
I have two observations.
1. After getting my first blister I believe it became EASIER to get more as the later ones all seemed to occur in the same part of my glans.
2. Baby powder on the glans has been very effective at preventing blisters. I wear it under a silicone glans protector (AKA as a toe protector). Believe the baby powder dries out the skin which apparently makes blister formation less likely.
That’s my experience too. I don’t know why the baby powder/talc works, but it seems to help a lot. As I mentioned before, I also use a bit of tape, and that also seems to help reduce the fluid buildup. Like VKN, I kept getting recurring blisters in the same place. It seems to take longer to recur when I let the skin heal completely, with no additional redness in the area. Cutting down the length of a set and the weight reduces, but does not eliminate, blister recurrence. While I’m healing, I use a compression hanger to reduce the stress on the skin.
But the only thing that has done the trick so far, for me, has been the combo of microfoam tape, talc, and silicone cap under the hanger.
Live long and prosper.