Need: Cross-Guild Bank Management

[Wrathaden]

Hello! I'm looking for an add-on that can handle guild bank inventory info in a way that I can't seem to manage on my own (or with multiple other add-ons I've tried). Here are the details of my predicament:

*We have 4 guilds with full banks (4 guilds on the same server with our inventory spread among them in a very organized fashion)
*We have 3 trustees who coordinate and access/restock these banks multiple times per day
*Each trustee has a toon with full access to each bank to coordinate swapping/transferring stock
*Keeping track of inventory and where everything is located/transferred to = disastrous time suck...

What I am looking for:
*A spreadsheet-type end result that can display to me the name and quantities of items in all four banks (ie - one column of the item names, one column each for the four guild's quantities of each item, one column for the total owned by all four together)
*The ability to be updated regularly, ideally via accessing each toon and each guild bank and either typing simple chat code, running a macro, clicking a button, etc.
*All of our three trustees to be able to access this inventory (no access to guild members, and I'm fine with this being a spreadsheet on Google Docs or something similar outside the game)

If all my dreams came true, this add-on would also have: (these things are certainly not necessary!)
*An extra column with the visual image (icon) for each item
*The entire thing be searchable via name of item or quantity (query to find out low/high stock items)
*The whole process of scanning and updating each guild bank and overall inventory would take up mere minutes of my day instead of manually counting all this stuff up and typing it into a spreadsheet for hours...
*It would be mind blowing if somehow, this could be viewed and referenced while in-game via some form of pop up window with it's own UI/settings.

I know the information exists, somewhere, because add-ons like TSM reference it in tool tips (it will show me how much of each item is in my bags, bank, guild bank, other toons, other guilds I have toons in, etc) so I desperately hope there's a way to accomplish all of this. Unfortunately, I don't have the know-how to code something like this myself.

If anyone has any ideas, suggestions, or would be willing to take on a task like this to build what might be a very popular add-on for all guild bankers out there... please let me know. Thanks so much!