This is more an overall suggestion, but seeing as this mod strives for realism for in-atmo flight I thought it'd be a good place to bring it up. I've seen it mentioned a few times here and there, but not seriously implemented. Fuel should primarily be carried in the wings, not the fuselage. It's how actual aircraft manage to be so stable, it keeps the CoM as close as possible to the CoL. It's especially important for low mount wings, which tend to have a low center of lift. For larger planes, CoM limitations and the actual CoM are expressed in references to mean aerodynamic chord. That's used to calculate the chord for tapered or swept wings (most airplanes), and it gives you the aerodynamic center (center of lift) of the wing. Just some food for thought!