Why does storage need to be adjusted to accommodate it ? Simply make large volume items stackable.
Players have always created storage chars so space is no issue.
As one who inevitably fights storage space, I tell you that even making parts stackable will consume storage space before long. Not in regard of the item you want to use yourself once its complete, but parts of weapons you intend to sell (like wiz or tao weapons if your char is war).
If you got dropped full wiz weapon from a boss, it won't tie up your storage because you put it in TM right away. With parts, you might want to wait till you got all of them and only then sell - and here you have one storage space taken up for indefinite time. Usually it is more profitable to sell complete item rather than its parts.Also true if you can sell number of parts rather than one at a time (unless someone is anxious to complete his item and needs just one part for which he might pay premium price.
Making second acct for storage really shouldn't be an argument for not doing anything with storage space.
BTW my long term experience is that collecting even stackable items like for crafting in the end (by the time I quit the server or it closes door) I find it just taxed my storage and never was put to any use, some because I didn't have complete sets or because time made the items obtainable from crafting mediocre or useless.