You cant use trash bag when overloaded/max item count. Kind of a bummer when you goof from a champ and get filled to the brim with items but im forced to throw a ton of garbage on the ground till i can move items to the  trash bag.

  I suggest the use of UOsteam, and the creation of an organizer macro.  Once you have Steam downloaded and in use, you can use the organizer feature-- under agents-- to create a trash macro. The easy part is collecting trash items--by type-- and adding them to the list. The hard part is collecting each item individually for a one time use to make a solid macro. The alternative is using a hot key and the set container feature of the organizer system to get the job done. Basically, hit hot key one time to set containers. I.E. main backpack to trash bag. (this is done manually and requires these containers to be targetable) Then hit the hot key a second time to start the organizer macro, which fills the trash bag. All that is left is to clear the trash bag when it is almost full. It can seem like it is a lot of work for the initial set up and maybe there is an easier route to achieve this goal, but it works for me so I use it.