The best desk to have would be one where you are lying down and staring straight up at your monitors...
So you'd be getting pressure ulcers instead. Meh.
But you don't sit at your desk
all day do you? You would get up and move around as much as you would anyway, but you would be almost forced to eat at somewhere which wasn't your desk, meaning you wouldn't get bed-sores.
How would you position the keyboard on a lying station? on your lap?
I would, for once, agree with tp on something, and say an ergodox with a long connector would be the best board. Your hands would be in a neutral position by the side of you, and you would be using a trackball too.
Same problem, anytime you're bent at an angle greater than 105 degrees, you need neck and head support.
The neck and head support increases cranial pressure.
Not necessarily. Lying down in bed on a pillow doesn't increase cranial pressure. You would want a headrest that doesn't support the head, so much as the neck. One that goes under the base of the skull that supports the full weight of the neck and prevents the head from tilting back.
We are talking a 100% ergonomic workstation here, so personal preferences aside, it's what is best for the body as a whole...