to make up for my hijack, heres how i get rid of excess clothing...
i build a room (about 5x5 or so) with a bit of distance to the prettier parts of the fortress, sealed off by a door. this is where your garbage will go. also i build several doors in the access tunnel to the garbage room, to stop miasma and probably water. somewhere in that acess tunnel you branch off and build another, small room. this is where you will build either 2 levers or some other triggers for some bridges.
i designate a stockpile in that larger room to take up ALL clothing (i play with dwarves naked) and UNUSABLE armor. (look bottom right of the stockpile setting screen for some stuff there appear additional options, like usable/unusable for armor/clothes/weapons or "prepared food" for well ... food.) this stockpile is also set to only accept "light" materials like cloth and leather, no "meltables".
DO NOT USE BINS.
on one side of the room i build a pit with an atomsmashing bridge at the bottom. designate the pit to garbage dump while youre at it.
on top (would you call that z-1?) of the stockpile theres a tunnel with pressurized water in it, held back by a floodgate. the floodgate and the bridge are both linked to seperate levers outside of the room.
once that stockpile is full, you lock the door, open the lever to the water tunnel and pull(r) the bridge lever. all your crap will be washed down to the bridge and atomsmashed.
turn off the water, keep pulling the other lever a bit longer (water gets destroyed, too), and repeat once the room is full again.
there are some things to consider about atomsmashing, tho: afaik the only part that "smashes" items at this stage of the game is the line of tiles the bridge raises to. if you happen to drop items directly above those tiles, while the bridge is up, they wont fall down, and wont get smashed.
to workaround that i usually have a retracting bridge right over the raising bridge. it pulls in a different rythym than the raising bridge, and therefor has the ability to "remember" items to fall down.
i use this same thing to get rid of whole sieges, right at the entrance, but beware i made the game crash reliably doing so, but i THINK that had somehting to do with the amount of stuff that was linked to the pressure plates. (i only used 3 to trigger around 12 bridges in a weird rythym).
In other games it worked a charm, and if you keep it to your garbage room, it shouldnt be a problem.
oh and something else... i never manage to get my pressure plates triggered by citizens, only by their pets. i havent tried the idea yet, but my plan is to chain a wardog next to two different pressure plates linked to the atomsmashing bridges, so they cycle in different rhythyms all the time.
something else;
i THINK if the clothing in the fortress is still belonging to someone the only thing you probably can do is make sure every dwarf has his own cabinet. amirite? somebody? altho they MIGHT just store that clothing in a clothing stockpile but NOT dump it. and thats why the water thingy is that helpful.