How much larger would a Deutschland with three triple 11-inch turrets need to be?
Short answerRoughly a turret length longer, plus clearance, most likely with two turrets forward and one aft.
NotesThe redesign begins with the existing turret footprint. The hull must grow by roughly a turret's length plus clearance for the mounting's working and firing arcs. A two-forward, one-aft battery would be the sensible arrangement, although German designers might consider alternatives. The answer turns the broader 'cheat properly' argument into a concrete explanation of the space that an extra major mounting consumes.