Very nice idea and I think it's possible with a community like ours on Drachenfels.
It depends, as you already said, on the number of players patricipating.
For the beginning it would be good to run the event once a week so we will see if there are enough players willing to help and to fill all the town treasurys in a short time.
The order of towns must not in alphabetic order. We could start a poll to support a town that needs the gold first and then try to balancing the treasury between all towns.
Community should stand in first place. Perhaps there are some RPG issues between towns. This should not affect the collecting.
Random places would be better I think to prevent it to get boring by the time.
There will be some things to dicuss. I will definitely be there when it starts