quick ideas:
Round thing at the back, i dont think it should be a sphere, keep the same size, but make it a cylinder, sticking with the current Rhineland engine style (what are they? big turbochargers?:P)
also, the bridge would look more rhinelandish if it was placed forward, but i really like the way your model looks where the bridge is now, maybe keep it just to mount turrets on.
texture it green and give it some of those circular turret mounts on the side and it'll fit in well.