Interesting idea, except for the fact that the Pyramidion, is one of the smallest ships in the game. Along with the fact, that it would need at least three engines to work with how they've programmed this game (I think that's true, I may be wrong). Light engines provide mild forward thrust, and turning thrust. Main engines provide the vast majority of your speed, but no turning thrust. So I think you'd need at least three engines.
It depends on what you consider small. To me, Pyramidion is one of the medium-sized gunships (along with Junker and Goldfish). But to be honest, that's exactly the point. I don't want another hulking Galleon, but rather a compact, yet tanky ship.
Now to the engine issue. I've popped
the engines' wiki page and found these two things:
"The heavy engine is positioned in line with the airship's center of mass - making it only affect the horizontal mobility of the airship. Light engines are positioned off the center of mass of the ship - making them contribute torque to the airship - affecting both the horizontal and the angular mobility of the airship (i.e. turning)."
"The mechanic of turning employs the light engines. The engines on the side you wish to turn towards generate thrust backwards, while the opposite side's light engines generate thrust forward, thus turning the ship."
From what I understand, the heavy engine has been always used only to propel the ship forward, which is the reason why it has no steering programming. However, the second paragraph describes how the steering actually works. I believe that with some special programming just for the Nimbus, it is possible to turn it into the steadfast charger it is supposed to be. But in case it doesn't work, I have two ideas where to place the main engine:
A) Bottom deck. Located on a balcony behind the staircase. This means more burden for the gungineer to take care of, but also makes it more challenging for the upper deck engineer, since he will have to use the hole in the upper deck more often for emergency purposes.
B) Upper deck. Laying on the back of the ship, exactly under the balloon platform. This will tie the main engineer to the top deck. While the gungineer will have more time for gunning, the upper engineer will have to really think twice before using the emergency hole, reducing it to a situational niche.
I personally enjoy challenge as an engineer (yes, I'm one of those masochists who like manning a Squid), so I would prefer plan A for gameplay purposes. But the plan B makes the Nimbus easier to maintain in case the original idea is too hard to implement.
Attaching my glorious Paint schematics as always ^_^
EDIT: BTW thank you for your feedback and for raising important questions. Keep them going guys. ;)