Hi Deteragram ,
I am by no means an expert on the subject, and you are most probably more experienced and therefore wiser than me. Nevertheless, I have given the subject of hoarding much thought as it is a problem we also have in our family. Of course, ultimately your conclusion may be the healthiest - that in the end there may be absolutely nothing we can do to get rid of the crap itself... however...
The feeling I get is that the act itself is fueled by a deep rooted fear - that the world is slipping through our fingers. If we can only grip it firmly enough, it will not disappear in front of our eyes. The fear is very personal, it is about leaving something behind, about being remembered, about remembering, and ultimately boils down to the fear of dying.
Of the many actions that I have attempted (including secretly throwing stuff out at night - usually ends with the stuff inevitably finding its way out of the garbage), the most effective seems to be just listening to the person, and simply trying to understand them.
Have you ever tried to ask your mother about it, with genuine curiosity? Something as simple as "why do you think you hold on to all that junk?". But not in an accusitory way where she may suspect that you are just hatching a plan to toss one of the boxes...
In the most delicate, and loving way possible. Simply to understand, and not to change her.
I find that just listening to people allows them to reach a point where they slowly start to open up to you. It is our fears that drive our illusions, and sometimes our fears are so deep, that we may not even be aware of them. It is only when we are 100% comfortable that we can even approach the thought of the skeletons in our closet (pun intended).
Whatever you do, don't try to toss anything against her will. She will only cling on with more strength!!!
More or less (crap), the only reality we ever have is the present, so just enjoy your time with her, whatever the environment looks like.
I share your concern, and wish you and your mom all the best.
Cheers!
Daniel