I think adding an aircraft carrier would continue the idea of a modern yet WW1 themed game. Space travel has been achieved and you're fighting in space, why wouldn't the military develop a space carrier? I have never found an engine mod or armor mod for ships so maybe that's where you could find them. Maybe add a ship that you can steal too, like a interceptor or a completely new kind of ship. Would be cool to add that as a prize that you could use for a contract/the market.
The carrier would have navy forces or security forces on it and would be rare.
Probably not at the top of your priorities considering the bugs and crashes that happen, and Marauders has a small dev team. But a map expansion or crafting expansion of some sort would be really cool in the future.