Yes, windage is a main issue. I am thinking of an open-bridge design, like the Maine Cat 30 that I used to own. It had standing headroom in the hulls, and kept the windage down by having an open bridge deck with roll down plastics, so you could choose between windage and protection depending on circumstances.
The other thing would be that having the bunks crosswise in the ww hull, with no walkway next to them, means that you only need standing headroom in the very center; the head and the companionways down. The hull could be sloped over the bunks. I am undecided if it should be permanent, which would mean only one occupant would have sitting headroom, or if it should be "hinged", so that you can raise the forward end while at anchor.
In terms of fitting it in a 30' ww hull, each bunk would take 5', companionway 2.5', head and closet 8' (which would double as galley space up top), for a total of 23', so it seems like it is doable. Standing headroom would be required for maybe 15' of that total.
I expect it is pretty cramped, but I would rather be cramped on a boat I might be able to own than admire someone else's boat that I will never set my foot aboard <grin>
- Gardner