Well, if there were not enough ammo onboard Shinano, to rearm extra planes, I can find only one probable scenario:
Planes start from CVs, out of enemy range. Fully armed, and fueled, they strike enemy CVs, and when they return, they will land on Shinano (which is far closer, than other Japanese CVs) to refuel, and return to their mother CVs.
Actually, in-game, planes CAN rebase to other CVs, but their original CV should be nonoperational for that.
The other solution would be to introduce special plane type, with greater range, and HR, that they can only be used, when Shinano is present closer to enemy. Obviously both solutions are complete waste of time [:D]
Anyway, it seems any use for Shinano will be to define its airgroups as Replacement Squadrons. Not quite-historical, but it seems to be only possible difference.
Have anyone found where Shinano planes should came from? I have only read account of some PH veteran fighter pilot, who said that they were training for Shinano.
ORIGINAL: Shark7
With the PBs, I guess you could go do minor bombardments of the undefended Chinese bases along the coast, Pakhoi etc. I think the PGs and PBs can do that, but I'm honestly not sure, haven't tried it in a while.
PGs can definitely bombard enemy. I have done that.