raystuttgart
Civ4Col Modder
I have actually already done this as part of my upcoming "super forts" release.
Well, if you already implemented that piece of code, please commit it to SVN of the main mod as well.

(Then I don't need to waste my time writing it.)
The only remaining bits are the min\max export limits and the new "trade groups" features along with "super forts" and some refactoring I've done to the forts\monasteries code. The "max" in "min-max exports" is basically to make sure that an automated trade carrier (wagon, ship, etc.) does not exceed the capacity for that yield listed in the destination. It does some sort of "forward prediction" while picking from the source itself using current production\domestic consumption, etc. The "min" was already existing in R&R.