In A LIBERTARIAN THEORY OF CONTRACT: TITLE TRANSFER, BINDING PROMISES, AND INALIENABILITY, Stephen Kinsella provides an argument for certain inalienable rights. It is in the section Clarifications and Applications towards the end. The whole essay is interesting, but you probably don’t have to read all of it in order to understand his argument. Anyway, he brings up many of the criticisms you have put forth, and he explains his reasons for certain inalienable rights. He explains his theory more in depth than Rothbard, and he considers his theory to be different than Rothbard’s.
As I just said to Autolykos, Rothbard does include the body in the will, so Rothbard does consider the body to be inalienable property just as Kinsella does (even though Kinsella is critical of Rothbard’s theory regarding the will). I don’t think Rothbard’s theory has the problems that you and Kinsella claim, I think that Kinsella explains it better and more in depth.