Edwyn and Invertedisdead,
Have you considered a standard wraparound head, but with thicker material underneath the dish. Drill holes from the outer edge of the thick base, radially through the base toward the center. At the center, they meet up with the outer ring of their own set of shower head vertical air holes, at a right angle.
This would give you a wraparound showerhead design, that would take standard and D-Nail dishes, and would have the airflow of the ShowerHead. No new design, just thicken the base, use the ShowerHead nut/threading/diameter, and drill some radial holes. I'm thinking you could easily get 11 radial holes this way... plus the normal 5 center holes, you're at 16. That's almost the Showerhead's 19!
It'll work, I tell ya!