Ooo like the hay bin idea.
My quad are in an 8 x 6 shed, no run yet (recently moved). I reakon that would be fine with a run attached.
The hares have a massive 10 x 6 shed (also waiting for a run) which seems a really good size. Even when the quad were in a 10 x 6 shed with a 10 x 6 aviary attached (at our last place, how I miss that garden) I wanted something bigger for them. Its so hard seeing them enclosed ...