Wings won't work in game without a horrendous amount of complex stuff going on. It's much more than just a case of 'add lift'.
Cockpits would be pretty, but would take away from the bit-part nature of SFS, same with any other pre-fabricated sections.
Some form of jet engine would be nice. But because of how heavy everything is in game, the thrust they'd need to generate to lift anything would be massive. And the engine would have to be massive as well.
For example, the most powerful turbine engine in the world is the GE90. Depending on specs, it's nearly 4 metres wide (8 squares in-game), 7 metres long (14 squares) and weighs 8.7 tons. For this, you get 569kN (according to the Guiness book of world records) of thrust.
Compared to in-game rocket engines, it gives you 30% more juice than a broadsword, for more than double the weight and 4 times the build space.
This wouldn't be a problem in a 3D game, as you could side by side them and create the thrust you needed that way. But in a 2D game, building a space plane from a side on perspective would limit you to 1 GE90 engine, maybe 2.
And they're not designed for speed, so they'd become useless over 300m/s or above 12,000m in game.
You could use the RR Olympus engines from Concorde. They're suited to high speed (Mach 2), high altitude (60,000m), high efficiency tasks. In-game, 750m/s ish, 20,000m. But they 'only' generated 142/169kN of thrust and with all the wing in the world, you're only getting 200t into the sky. Which isn't a lot.
And worse, they'd be shrank down (like all engines are in game compared to their real world counterparts), which means a real nerf-hammer as well to their capabilities.