Additional furnishing storage / housing storage will increase loading times for entry wherever said proposition would be introduced; if it is even possible.
The best advice concerning space is to maximize current offerings of storage, bags, sacks, satchel, case, locker, wardrobes.
ORGANIZE properly. Send anything you're not currently intending to use within a few days to a mule character. Maximize inventory on mule characters.
Evaluate if an item is worthy of retaining for your personal use. If something is unworthy, there's means of selling unwanted items. In the case of things that can not be sold or reclaimed at A.M.A.N. NPC or the Bayld NPC, often choosing to drop something is just the best option.
Inventory 101 BG-wiki ~
https://www.bg-wiki.com/bg/Inventory_101