o-r-o to collect refuse from outside. Ayup, problem solved.
Why don't you just collect the crafts in bins in the stockpile closest to your workshop, and then have the workshop closest to the trade depot take the bins slightly before the caravan arrives? That seems to be a lot more simpler. When you're done, just stop the stockpile from taking from the other stockpile. I've never really had this problem as my crafts stockpile is directly below my trade depot, crafts workshop directly below the stockpile, and stone stockpile directly below the crafts workshop. I think the main problem here isn't UI or lack of features, but a clear lack of fortress design experience.
Or you can just move the bins to the trade depot, it's like 20 hauling jobs if you have a decent stonecrafter to buy the caravan and it's honestly less than "move to workshop, haul to stockpile near workshop, move elsewhere, move back to stockpile, move close to depot, move elsewhere, move back to crafts, move crafts to depot...' My plan is simply 'move to crafts workshop, move to stockpile, move elsewhere, move to stockpile, move to depot'. It's the same minimum distance no matter how you do it, you're just adding extra hauling jobs and distance.
Lets say your dwarves chill in the meeting area 10 steps from everything. Every time they finish a job and have to wait they move back to this area. Every time you add a new hauling job and then have them wait you're adding 10 more steps into the equation to move back to the meeting area and 10 more to move back to the new job, wasting more time than you think you're saving. My second plan at worst adds 30 steps into the equation, yours adds 50 steps.
Wait, why would you move the crafts
away from the trade depot? I make sure my crafts stockpile can't accept any more crafts before I release unsold crafts, that way there will be no hauling to the crafts stuck in the depot. Next season I just mark them and they're up for trading instantly.
Wiki. Use it.