Part of your idea would have required me to come up with the massive list of items all the different keys hold. Instead I just ran with it and came up with another good solution.
I've posted the script in my script thread:
Epi's useful EasyUO ScriptsIt asks you to select an empty bag in your pack which items will be moved to and opens it. It then asks you to target a container to move items from, opens it, and then asks you to target an item in the container. It will move 20 items(changeable) at a time rather quickly until you are at about 300 stones(also changeable). Then it will cycle through all your keys, doing "fill from pack". If anything is left in the bag it will determine the item as non-storable and will move it back to the container it came from.
Sound like a lot, but it runs pretty smoothly.
