Blitter, can you at least take the stuff to your local charity? Would not it feel better knowing that somebody else could find a good use of the items that you want to discard?

It does sound very hypomanic. In general, too much of very pointed goal-oriented activity is a sign of hypomania.

Another idea is digital mementos. If you take pictures of the stuff you are about to discard, it would slow down the process quite substantially.

I would post lists of unwanted items to your local FREECYCLE mailing list:
https://www.freecycle.org/browse/AU

On Freecycle, stuff is usually gone within a day. And you can put stuff outside of the house and not even see the people who would pick it up - unless you want to.

It seems that you crave the finality of the garbage bin and giving stuff away does not provide that finality. If that is the case, maybe you can use a proxy method - once you post on Freecycle, print out the post. When folks have picked up their item, burn the printout.