I've ordered a couple prototype knobs now - should be with me in about a week.
The thickness of them is about 11mm, thats about as thin as I can get them while still retaining some strength so I don't know how comfortable they'll feel when you shoulder the gun. The cheek piece adjuster would probably be best left as a grub screw I reckon. You might get away with the Length of Pull adjuster not digging in you too much though.
Here's a rendering of what I think it might look like : (the knobs diameter to the tip of the knurled bits is 27mm I think, can't remember - it's something like that though - about an inch)