Does the common-hull plan account for RAF Bomber Command attacking the German ports?
Short answerYes; Britain bombs them as it did historically, but those raids did not prevent Bismarck and Tirpitz from being completed.
NotesThe scenario does not assume that German yards are immune from British bombing. RAF Bomber Command attacked the relevant ports and construction targets historically. Bismarck and Tirpitz nevertheless reached service, so the same raids are not enough by themselves to make the alternate schedule impossible. The available medium-bomber effort is more likely to disrupt construction than to destroy the program outright.