I like this, its something we briefly discussed with Classical Warfare AEA, just not really sure how to implement something like that. You would hold it at your storehouse until its transferred somewhere else ie cc, forge.

The idea is to turn storage buildings into actual resource containers, so the economy becomes spatial, resources are stored locally, not globally. If you deposit 500 wood into a specific storage, that storage literally holds those 500 wood. If that storage is attacked, up to that exact amount can be looted.  

fields can't not be built within 50m of CC in CWA if you want to see what its like

I think your advantage were forge upgrades.  The AI did not get any of them until it was too late in Endgame. Nevertheless the german 2 slinger brigade trained from 2cc were two unbelievable lucky guys.

Regarding your first line, not allowing fields next to CCs was discussed not long ago, I don’t know what was the conclusion. I think it’ll be implemented at least in one mod for now. Regarding your second line... I'm confused about “storage actually contains resources”, RTS don’t tend to work like that… not that that’s an invalid mechanic, just that you are stating it like it’s the obvious default, if I even understand correctly what's going on.