What makes a capital-ship carrier conversion worthwhile

What would a decent carrier conversion of a Derfflinger-, Mackensen-, or Ersatz Yorck-class battlecruiser look like?

It could resemble HMS Eagle on a faster, larger hull, but Germany's need for battle-fleet strength would make the conversion strategically questionable.

Eagle's hangar is praised as exceptionally tall and spacious for a capital-ship conversion of her size, although her battleship hull left her slow and relatively small. Transferring that arrangement to a larger, faster Mackensen- or Ersatz Yorck-type hull could produce a capable conversion. The strategic problem is timing: during the First World War Germany still needed capital ships for sea control, while carrier aviation could not yet perform the same fleet role. A technically attractive conversion could therefore remain the wrong allocation of a scarce hull.