My honest assessment is: you're much better at modern vessels than you are at WWII-era and earlier, especially at this stage.
BTW, are these supposed to be nuclear powered? That honestly wouldn't make much sense for such a small ship.
Diesel electric. exhaust system from Mecmar AS (a Norwegian company), with Mecmar you do not need any kind of funnel, the chilled exhaust gas (which is also cleaned Nox) can be sent out back or on the side of the boat without causing problems for others.
Many offshore ships in Norway use them (it is important for them to have 360 degree view when they work up to an oil platform)
Several naval ships have this system also, for example. Visby class and Skjold class. The Italian Navy, the French and some that I do not remember have ordered this system to their ships to.
The advantages are:
Cooled exhaust
Better against environment
ways much less than the system used in ships today.
you do not need to have any type of funnel.