Yes, I will model the exterior hull for the reasons you gave.
^^ And I agree with you! The steps in the pictures are wrong. No doubt.
My latest iteration has better steps in a different configuration. I plan to post images soon. Currently, the upper bridge module consumes most of my time. It will be a total new design, since neither of the available blueprints fills the area plausible (I include what Whitefire had in mind for the upper bridge module deck, but it will be on the lower bridge module deck).