As I understand it there was never more then ten. Was I wrong in this regard? I found the number from the Paris Peace Conference book. I was thinking in terms of a larger submarine force.
Well you did ask about an AH where the Germans place any number of submarines. You asked, and I answered.
However I don't think an increase in submarines would do much to change the outcome of the war. Britain had a fair-sized fleet operating in the Med. Sea, so its links with empire would be kept intact with minimal damage. Add to that the French Navy, and then the Italian Navy after 1915, and you have a substantially-powerful Entente and Associated Powers force to combat a wide range in increase of German-Austro-Hungarian submarine units.
Also, keep in mind that you're talking about a pre-war POD. Before 1915 submarines weren't recognized as prime naval material, and thus weren't produced in big numbers. You're having Wilhelm make decisions that didn't exist with the conditions existing in the rundown to war, unless you can decisively prove that submarines make an excellent naval force in a previous conflict, which is an altogether wholly-different POD.