Strangely in this situation, I think the end of the shed being stuck on the wound might actually help you. In a healthy tail, we recommend removing the stuck shed as it will cut off the blood supply and cause the tip to die and drop off. But in your position, this is exactly what you want to happen. By leaving the stuck bits of shed(s), the injured part will naturally dry up and drop off. It might just be a case of keeping the injured area clean, dry and uninfected and just making sure that sheds are successful as far as the injury. It will look a bit unsightly for a few months as the sheds build up, but it might do the trick.
One of mine had an operation which left her with stitches along two inches of her belly. The stitches dissolved, but shedding was a problem around the wound. For the first couple of sheds I tried to make sure the shed came off around the wound, but just ended up opening it in places. I then left the shed to build up, making sure that it came off everywhere else. After four more sheds, the entire area of stuck shed came away, revealing a nice clean, neat scar.
I think if you keep working to get the end of the shed off, you'll probably keep reopening the wound. Nature might very well have the answer for you.