Here's what I did.
3x3 stone stockpile, carve a track from wherever to wherever. Puts stops at each end, have it dump in the direction of the pile you want it ending up in. Set up the route with (h)auling menu, link the loading stop to the 3x3 stockpile.
Bam, they automatically clear all the stone in the fort, and place it in a quantum stockpile. Even better, it's a quantum stockpile that doesn't need any micromanagement. Garbage dumps are no longer needed. No unforbidding required.
EDIT: I'm actually doing that with every stockpile I have, right now. Adding a 2 tile track, side-by-side stops. They load the cart and dump it right next door. 5x5 room for each workshop, infinite storage. It's an automated undump with no tricky water, or micromanagement.
I could see this working very well for trading. Set up a couple stockpiles next to the depot, and when you buy out all the elves' cloth or whatever you fancy, it gets put into the stockpile, then shipped off next to the dwarven tailor to make into beautiful socks.
Honestly? This is working very well for EVERYTHING. My normal level with 11x11 stockpile room after room... Isn't needed. I have my ores dumping in the middle of my magma smelters, my magma smelters drop the bars into a pile. That get dumped into the middle of my magma forges. From my magma forges, items get dumped into a pile, that also have my magma kiln and my magma glass furnaces dumping into it, as well!
Clay is a ways away, so I have clay collection zones, overlapping clay stockpiles. Haven't started this one up yet, but it should load the clay into a cart, and dump it into the middle of the 4 magma kilns. Going to try the same thing with sand bags next.
As I mentioned above, wood is getting dumped down a chute from the surface, the cart triggers a bridge to retract and drop the wood. Fast access, little risk of a flyer getting down. I could do the same with clay and sand bags, if I didn't have surface magma.
This update is nuts!!! :-D
EDIT: PS, wheelbarrows are worth it. They go so much faster, and it's really fun to watch it, too. Great mental image of em whipping around corners, barely missing things...:p