Supporting more German surface raiders takes resources from U-boats

Could Germany support a larger surface-raiding force?

Yes, by concentrating resources that would otherwise support submarines or other forces.

Germany could support a larger surface-raiding force by concentrating its limited resources. The additional support would have to come from existing commitments. In this scenario, the U-boat force is the principal source of those resources. A stronger surface concentration would leave less support available for the submarine campaign.