German naval plans from pre Hitler years included an aircraft carrier and 6 new larger Panzerschiffe with third triple 11" gun turret turreted secondary 6" guns. Range was same as was speed. The cruiser fleet was to be expanded to a dozen ,with 6 new builds....presumably to escort the carrier, and raid under its direction?
Rader had a hand in this. (My opinion only, YMMV.) He really did not understand the naval trends and professional naval thought too well. I think he to a certain extent was reading British naval thought and might have picked up on how the British were trying to integrate the carrier into traditional battle-line tactics as a scouting element, but missed out on how the British were also thinking about independent raiding with this unit.
Initial plans were for the three new Panzerschiffe plus the existing three PBS, but with the Hitler regime more money became available and KM plans were drawn up to expand to include either 6 heavy faster battle cruisers or 8 heavier faster PBS. Little mention is made of the aircraft carrier or the lighter cruisers... so everything is up for grabs, however Hitler crushed most KM expansion plans in 1934 insisting the fleet be mostly Baltic/North Sea fleet.
That tracks well, but does not explain Rader's continued insistence on the Z-plans.
The next year however Raeder was able to convince Hitler that a modest surface fleet could be valuable against the French. From that point on all new planned warships had to be anti French designs , so everything changed into the useless fleet the KM ended up with in WW-II. Range and reliability didn't,t matter anymore , but speed was critical as was firepower.
That is interesting. It explains so much about why the ships the KM receives after 1936 make no sense at all considering the likely naval war they should have planned to fight.
So anything else is preferable. In 1930-1932 an aircraft carrier is planned, but by 1933-34 no mention along with new cruisers. In the following years [1935/36] one carrier [GZ] was ordered and laid down along with 3 heavy cruisers. No mention of the light cruisers until late 1930s .
In effect, this is the kind of planning one might find in a dictatorship, where the flavor of the month drives the procurement decisions. This hurts a navy that has to have some kind of stable long-term planning, which is kind of why I think ATL mods to the pocket battleships would have been pointless. The PBS's were designed by the Weimar regime's planners. They had a vision of 19th century commerce raiders that makes a kind of cockamamie sense and designed surprisingly well to it. Quibbles about bulbous bows and transom sterns are nice speculations. Wishing for dual purpose armament is nice, but seriously? The best improvements the Germans could have implemented with this class of ship is crew training. The captains especially, as they are the ones who have the independent raider ship conundrum. That is not a criticism. The German of 1940 navy was schizophrenic in its expectations and desires from these captains. That it, the surface fleet, as a fleet, could be effective (Norway) when it had a clear purpose and mission is clear. Materially, for a small surface fleet, it pulls off some quite impressive early operations. Nothing wrong with its fighting spirit.
But that is not what the panzer ships were designed to do or what the captains assigned were supposed to do. These are hit and run singletons. The captains have to be bold timid like Raphael Semmes. The raider design adopted might have been a bit oversized for the mission. If I suggest technical improvements, it is in the margins, such as engines (diesels put a lot of noise into the water which British hydrophones can pick up at almost 30 km, whereas turbines only show up on sound gear about 5-7 km away.) Mechanical reliability uber alles. Shells and torpedoes need to work. At the Platte they didn't.
So as alternative you can reasonably go in any direction from 1933-34 on. Having said that I wouldn't waste any new production on any new idea, but would be willing to decommission and modify surplus warships to find out.
There were discussions in the mid 1930s on possible integrated battle groups with carriers + battle cruisers & heavy cruisers plus flotilla of Zerstroers - in order to better employ the wolf packs.
The battlegroup theory seems at first glance to resemble the task force concept, but the failure to take into account the need for a fleet trains or fleet logistics in general, shows that the thinking here is rudimentary. When even the British fail to understand this fundamental feature of carrier operations, it is not a harsh criticism of Rader. The Americans took a couple of years themselves to figure it out.