A light cruiser for trade protection (1921-style)

Major navies had a definite need for a light cruiser for trade protection (in the period from 1903-1945). For 1912, an 8,000 ton ship is a very reasonable size. My initial estimate for dimensions would be 555ft x 57ft x 18ft, with coefficients Cp=0.56 and Cm=0.88. This is only very slightly more than 8,000 tons. I would like to see a speed of 32 knots, as that seems to be the minimum acceptable speed at normal displacement. I would go with a 9-6in/50 gun armament with a secondary armament of 4.7in/50 guns.