I dunno. Organic space suit implies that the nervous system could survive independently of it. But it can't.

You need to get blood to the brain, so you need a heart. That blood needs oxygen so you need lungs. You need some way of getting energy to these systems, so you need a digestive system, which starts at your lips and forms a frighteningly long tunnel that ends at your butt. Now you're introducing weird shit to your blood beyond just oxygen so you need a few systems to keep the blood clean. Now you've got all kinds of different needs and so you have other orgasms to keep those organs alive and functioning. Oh and because your blood is also alive, it dies and you need a way to make more. Quite efficiently this is done in your bones. But for the sake of argument let's say this is possible without the bones themselves.

I'd say the space suit starts at the immune system, and ends at the skin, which is really an extension of the immune system but there's muscle in there. You could, theoretically, survive without any muscle or skin, or even an immune system in a clean environment, as long as you had a way to obtain calories and Oxygen independently. Though going to the bathroom would be hard.