I'm pretty sure that the hull detail, including the scale-establishing portholes, was only ever applied on the Aurora herself. The other two appearances (the ship at the beginning of "Operation: Annihilate!" is also this type) probably featured an, uh, featureless version whose scale thus is for the audience to decide.
In theory, the ship of Leo Walsh could have been of the Aurora specs, if his only freight was Mudd and the three settler wives. Or even if he originally hauled Mudd and forty settler wives, and this was the tail end of his rounds. The portholes suggest two decks and an approximate hull length of sixty meters of so (including the engines).
Timo Saloniemi