Still, I think the idea of prolonged slow strangulation is really hot, and there's a number of ways to make that happen. A machine is cool, so is a block and tackle, so is being noosed while standing on a pile of books... and your buddy slowly removes them, one book at a time. (For more stability, two stacks of books, one under each foot. Remove a book from the left stack... pause... remove a book from the right hand stack...)
There's also noose hogties, another favorite setup of mine.
Madeira, I like the way you think, and your bondage art is super hot.