I have done a lot of drawings based on the British Hawkins class cruiser hull. The Hawkins class was built to counter German raiders on the high seas. So I put my German hat on and tried to figure out what a Medium sized cruiser could look like with a completion date expected to be 1918-19. As normal with a raider the ship would have to be able to defeat the normal escort that might be guarding a convoy on the high seas. These would generally be light cruisers of the Town type or older armoured cruisers (County type) that would have the range.
I ended up with a 500 foot cruiser armed with 8 x 170mm. The German 170mm was better than the British 6" and 7.5" that would arm the escort cruisers listed above. The 170mm gun and turrets were already available on the older pre-dreadnought battleships which could have been used to speed up production to get the ships to sea if the type had been proceeded with.
Displacement: 7,800 tons normal, 10,750 tons full load
Dimensions: 511 x 56 x 23 feet
Machinery: 2 shaft, turbines, 60,000shp
Speed: 30 knots
Endurance: 12,000 nmi at 12 knots
Armour: 4.1" belt, 2" deck, 2.75" turrets
Armament:
8 x 6.7" (170mm) (4x2)
6 x 88mm (6x1)
Torpedoes: 8 x 19.7" (500mm) (4x2)
Crew: 580