We have a hammock - it's great! I would measure it for you, but DS is sleeping in it at the moment
Have you thought about hiring one instead? I know that the West Auckland Parent Centre has one that you can hire, or there is the
Baby on the Move site.
That way you'd get all the paraphernalia with it - mattress, spreader bar, door clamp, hooks, chain and spring etc...
Just a thought.