Thanks for all the replies!
The justification for this ship is this:
While a large USS Montana sized ship could be built, a Montana cannot be in two places at once. As such, it is considered better to have two lesser hulls instead of one great hull so as to have more naval presence in more areas. However, to augment the problems this creates, a number of adjustments are made to the doctrines used by the Navy.
The main doctrine change is extended use of land based air support. The skill, training and investment is not there at the time these ships are needed for a major investment to be made in carriers. The type of distances involved when it comes to this ships patrol range and its proximity to land based air support greatly negates enemy carriers, which at this stage of the war have taken major losses. Carriers are being developed, but the wars focus means that they are not being being focused upon strongly.
Armor has
not been heavily sacrificed in this design, firepower has been. The ship still maintains good speed and its armor scheme is heavily concentrated around the two front turrets and engines. The ship cannot have its T crossed, as doing so allows the ship to angles its armor for maximum thickness while still maintain full firepower. The ship is well equipped to charge an enemy vessel head on, angling its armor as it moves. During a retreat phase, the ship relies on its great quantity of 5" guns, smoke from escorts and land based air support to cover itself. The ships also work very well in groups, as treating naval forces as a unit and not as single ships was another doctrine change brought about by developments in communication and training.
The navy this ship belongs to had fairly modern cruisers at the start of the war. Light cruisers were about the only ship it had in decent quantity and with fairly modern designs. Heavy cruisers were available in smaller numbers and with less quality with capital ships being even fewer in number and even less advanced.
There are battlecruisers, standard battleships, pocket battleships and fast battleships. For my own AU, I am creating this class as a "Maneuver battleship", as it has qualities of a fast battleship and a pocket battleship
I also have another design. Similar, with 22, 5" guns and one large quad 16" turret. This one leans even stronger towards being a pocket battleship.