Anyone interested in developing my Oblivion Inventory is a backpack mod to Skyrim is free to do so.

Purpose of mod:
Realism. Drop the backpack in combat to minimise your encumbrance. Best when partnered with an encumbrance mod like my Encumbering Loot Armour and Weapons or a weighted gold mod.

Here is how it worked in Oblivion:

• When you dropped the backpack, all items not equipped, not a quest object, not hot-keyed would be removed from your inventory.
  
• When you pick-up the backpack, all those items are return to your inventory.

Other features (container easy-sorter) of the Oblivion version:

• When you put the backpack in a container, you automatically put all your items that are not equipped, not quest objects and not hot-keyed into the container.
  
• You can use the container's current contents as a filter. For e.g. if the container contains ingredients only, then only ingredients from you inventory are put in the container.

Here's the Oblivion version on Nexus: http://oblivion.nexusmods.com/mods/21721

And I already have approval from TreasureChest to use their Sabre Gear backpacks as the model. Just get approval again for your development.