A design study for a smaller Ger/BB/1915 CDV

I have a pencil inboard profile for a smaller coast defense battleship labelled Ger/BB/1915 CDV (Coast Defense Vessel). The ship is moderately well protected, has a speed of 20 knots, and carries 4-16.5in guns. The ship has an anachronistic look, with a tower formast and trunked funnel. The Springsharp design worked quite well:

Ger/BB/1915 CDV Early Version, Enter country Enter ship type laid down 1915

Displacement:
 20,836 t light; 21,691 t standard; 22,375 t normal; 22,922 t full load

Dimensions: Length overall / water x beam x draught
 581.00 ft / 580.00 ft x 100.00 ft x 25.00 ft (normal load)
 177.09 m / 176.78 m x 30.48 m  x 7.62 m

Armament:
      4 - 16.50" / 419 mm guns (2x2 guns), 2,246.06lbs / 1,018.80kg shells, 1915 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread
      20 - 5.00" / 127 mm guns (10x2 guns), 62.50lbs / 28.35kg shells, 1915 Model
   Quick firing guns in turrets (on barbettes)
   on side, all amidships, 4 raised mounts - superfiring
 Weight of broadside 10,234 lbs / 4,642 kg
 Shells per gun, main battery: 70

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 13.0" / 330 mm 325.00 ft / 99.06 m 16.00 ft / 4.88 m
 Ends: Unarmoured
   Main Belt covers 86 % of normal length

   - Torpedo Bulkhead:
  2.00" / 51 mm 325.00 ft / 99.06 m 23.00 ft / 7.01 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 14.0" / 356 mm 8.00" / 203 mm  13.0" / 330 mm
 2nd: 2.00" / 51 mm 2.00" / 51 mm  2.00" / 51 mm

   - Armour deck: 4.00" / 102 mm, Conning tower: 13.00" / 330 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 24,419 shp / 18,217 Kw = 20.00 kts
 Range 3,600nm at 12.00 kts
 Bunker at max displacement = 1,231 tons

Complement:
 914 - 1,189

Cost:
 £2.812 million / $11.249 million

Distribution of weights at normal displacement:
 Armament: 1,279 tons, 5.7 %
 Armour: 8,787 tons, 39.3 %
    - Belts: 3,093 tons, 13.8 %
    - Torpedo bulkhead: 553 tons, 2.5 %
    - Armament: 1,950 tons, 8.7 %
    - Armour Deck: 2,968 tons, 13.3 %
    - Conning Tower: 222 tons, 1.0 %
 Machinery: 925 tons, 4.1 %
 Hull, fittings & equipment: 9,845 tons, 44.0 %
 Fuel, ammunition & stores: 1,539 tons, 6.9 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   45,251 lbs / 20,526 Kg = 20.1 x 16.5 " / 419 mm shells or 8.8 torpedoes
 Stability (Unstable if below 1.00): 1.15
 Metacentric height 6.5 ft / 2.0 m
 Roll period: 16.5 seconds
 Steadiness - As gun platform (Average = 50 %): 87 %
   - Recoil effect (Restricted arc if above 1.00): 0.59
 Seaboat quality  (Average = 1.00): 1.73

Hull form characteristics:
 Hull has a flush deck
 Block coefficient: 0.540
 Length to Beam Ratio: 5.80 : 1
 'Natural speed' for length: 24.08 kts
 Power going to wave formation at top speed: 40 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 0.00 degrees
 Stern overhang: 1.00 ft / 0.30 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  26.00 ft / 7.92 m
    - Forecastle (20 %): 22.00 ft / 6.71 m
    - Mid (50 %):  22.00 ft / 6.71 m
    - Quarterdeck (15 %): 22.00 ft / 6.71 m
    - Stern:  22.00 ft / 6.71 m
    - Average freeboard: 22.32 ft / 6.80 m
 Ship tends to be wet forward

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 70.2 %
  - Above water (accommodation/working, high = better): 183.9 %
 Waterplane Area: 40,104 Square feet or 3,726 Square metres
 Displacement factor (Displacement / loading): 107 %
 Structure weight / hull surface area: 181 lbs/sq ft or 883 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.92
  - Longitudinal: 2.06
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is excellent
 Room for accommodation and workspaces is excellent
 Ship has slow, easy roll, a good, steady gun platform
 Excellent seaboat, comfortable, can fire her guns in the heaviest weather