Dead hangs are great, although they can exacerbate low back pain in some people. This video talks about the issue and offers some solutions:
(A good way to increase spine stiffness and stability is to do the classic
McGill "big 3" exercises. The advice is to do all of them daily, but personally I just do one exercise per day, then the next exercise the following day, etc.)
Shoulders can be a limiting factor as well when dead hanging, but there are ways to fix the problem, for example: