Update. Navigatonal deflector housing in place as well as lower support strut.
I'm also giving some thought to scale---how big this will eventually be. I'm trying to consider what sort of things will be required. If it's meant to survey Class M worlds and even land on them then a hangar bay will be required for the one landing craft. I'm thinking of putting the hangar bay on the underside of the forward section towards the bow. The nav-deflector housing also holds many of the ship's main sensor systems as does the end of the nose section of the ship. The ship's support facilities are mostly in the support section which is mid ship between the upper and lower ring support struts. Aft of that is main engineering and the four large sublight impulse engines. I haven't given it a lot of thought, but I have this idea that the serrated dark area of the upper support strut might also be some sort of hydrogen attractor/collector...if that even makes any sense.
I didn't really think about it before, but now it does strike me how the ship looks like a large heavy-lifting rocket laid on its side and then dressed up with added fixtures. In that context it doesn't look inconsistent with 21st century tech since I've seen contemporary rockets with that kind of shape albeit more elongated.