I thought about doing something similar for 2 smaller mills on one tower.
Basically make it look like a 2 engine aircraft, or get fancy and a 4 engine bomber
If it's useless junk for decoration only you can put up almost anything anywhere, but if it serves a usefull purpose people panic and you get hit with zoning, codes, restrictions, etc....
So, making a 2 gennie aircraft looking mill on one tower and hiding the wires inside the tower, it looks like a useless decoration or wind vane and probably no-one would complain about that in most areas! Plus it would look cool if nicely done.
In thinking about this alot, I have decided myself to keep it kinda small. Lots of stress on those pipes running out the sides, supporting the weight of the mill and the force of the wind trying to push them backwards. The more support you add the more you block the wind flow, plus more weight of course on the tower.
My thought is a small wing out each side, round body in the center over the tower, rear rudder as the furling. Perhaps to support the wings extend the tower a couple feet above the body, then run a thin guy wire to the outer wingtips.
Make sure it can't really fly in hard winds though!!