There must have been a door on my boat at some point because there are faint scratch marks in the coachhouse ceiling, it's been gone at least 20 years I think. As Virago Deb says "... for a reason...".
My head is on the starboard side opposite the hanging locker immediately aft of the v-berth. I put four hooks up, two on the bulkhead on the aft side of the head/hanging locker (the hooks are on the forward side) and two on the bulkhead aft of the v-berth. The hooks are as close to the ceiling as I could get. I have a piece of curtain with a bungie cord run through the hem at the top (not sure if that's what it's called but I mean the part where a curtain rod would go through). The bungie cord has hooks at each end. With this I can curtain off the head, curtain off the v-berth when I'm on the head, curtain off the rest of the cabin when I'm on the head and curtain of the hanging locker (though I don't have a reason to do this). I can also draw the curtain along the bungie if I want it completely out of the way. This arrangement seems to be sufficient privacy for guests.
If you do this you'll want the bungie cord to be reasonably tight but not so tight as to pull hard on the hooks as they will work loose. Also, make sure there is a a gap between the curtain and the floor so the curtain doesn't get wet or stepped on.