I'm currently trying to set up a temporary camp for an excarvation and have a lot of problems with supplying this camp. Not that it isn't possible, its just extremely annoying. A simple option to choose a specific place or stockpile for an item would make life that much more easier not only in this situation.
You know you can set the priority of the Stockpile higher, so they first haul items there
If you mean choose where caravans unload then yeah, that would be great!