Ventral View

For the lower hull markings, I wanted to have what the Constitution had, but things needed to be rearranged. The yellow circle, to my mind, is for the warp core or antimatter pods. So that is placed directly underneath the aft pylons, where I would put main engineering (the upper nacelle would have its own warp core in the saucer section). The irregular shape I assume is for deuterium tankage, so that is placed in the same relationship as on the Constitution. The small red square I assigned as the main tractor beam (used for towing other starships), so it too went in the same place as the Enterprise.

 

However, the remaining long grey rectangle had to be moved forward. On TOS-R, it opens like bomb bay doors to launch satellites. Furthermore, on the Enterprise there is a larger red square underneath the shuttlebay, on the undercut. I figured that was the main cargo bay hatch. So these two things still needed to be associated with the shuttlebay on the Dreadnought, which is forward instead of aft.

Done