Autotax works for exports. You can link them to the castle chest!
It doesn't work for regular items (resources, etc.) sold to a stockpile, but it does if you sell to an export location. (I have seen it working).
Here it would be simpler, eliminate crafting, so no instead of stockpiles, (with exception of good for doors and siege materials) you can have export locations.
Resource collection could be a variety of things because now you don't need players to do all of it to supply crafters. You just want the visual effect.
Outside castle I would place sticks and no more. The rest I would place in a more or less divided (across castles) middle ground. Not far away though! That was the mistake of borderlands v1.
My main concern with the map, aside from this economic incentives, is to produce a small map. I would prefer a small map full of little places than a large map of empty spaces. 2 -3 castles would be enough for me. Then maybe a semi-castle for bandits.
We can talk about it.
My suggestions in brief:
- Small map
- Not many castles
- Castles should be worth keeping (exports tricks)
- No crafting! The first map to successfully exploit this new feature will be a success.
Then there is the issue of rational castle design as opposed to some lord of the rings fantasy...Pretty is good but functional is a must!