The saucer was
intended to be the drive system, or rather systems. The original concept was to turn the "saucer and rocket" idea that can be said to have inspired the original Enterprise
on its head and put the people in the rocket and the propulsion in the saucer. Nevertheless, even on the Enterprise
there are hatches on the saucer, secondary hull and even nacelles. The challenge is to provide clues to what the scale is without resorting to the features everyone always resorts to. Whether they would end up being mission modules related to the function of the drive systems, or plug and play weapons modules, or scanning packets, or whatever, the idea was to afford an opportunity to show little handholds and latches and writing, etc. which in combination with other clues would hopefully tie down the size. A little like the model of Discovery
I'm sure your idea will attack this problem with greater perspicacity and style.