Even if you share absolutely no items at all between all classes, you'll have enough room to store the new kabutos and snowman head. I forgot to mention that the usagi kabutos are ALSO one of those ancient tradeable seasonal items, and thus won't be storable. Best put them on a retainer!
Also, there's a reason I stress making things that are used in guildleves or GC supply/provision missions. Rather than selling to an NPC for piss-poor money, or selling on the boards and risking having it not sell at all, you can get bonus xp, other rewards, and achievement progress! Hooray!