Design group needs close look
It would seem that when the level, empty vessel was then loaded, it would list to the opposite side, would it not?
If the goal is to have the vessel level when empty and loaded, the best way would be a liquid (seawater) tank on each side with a pump and sensor. The pump would automatically pump sea water to the lighter side. This would keep the vessel level empty, partially loaded, or completely loaded.
Oh, and sea water is free.
As to the extra dollars spent on design and engineering, I understand that the ferry system employs a large group whose task is ferry design. So why is this considered an extra cost? I would like to know what this group's total salary, benefits, facilities, and utilities are for a year, keeping in mind that these are full-time positions, year round. They must crank out a lot of designs over the years!
Also, what are their qualifications? No, I am not a naval architect.