whatamess - (((hugs))) - I completely understand what you've posted. My 9-year-old has Pervasive Developmental Disorder (PDD), and he also rages. Often, he chooses to go into his room to get away from whatever is overwhelming him, but then he will throw objects, kick and scratch furniture and doors, etc. It really upsets me, because we can't afford to fix or replace everything he destroys. Recently, during one of these episodes, he unscrewed the heavy knob beadpost balls off of his bed and threw them at me (and his therapists). Had one of those hit somebody in the wrong way, it could certainly have killed or seriously injured. That's when we decided to remove just about every heavy, sharp, or hard object out of his room, including some of the furniture pieces. We even took his shoes out of his closet because he was throwing them at people. I have had him help clean up his disasters (after he calms down). But, in general, since he has SO many other more demanding issues, we clean up after him a lot, and we only give him small chores of which he doesn't feel so overwhelmed. Also, by removing a lot of stuff out of his room, he is no longer able to make such big messes.
I don't have the answers for helping your son calm down during the rages. I sure wish I did. Our son hates to be approached, touched, or soothed in any way when he is upset. He is not able to easily calm down or consider options for solving his problems. These are things we and his therapists continue to work with him on, and I must say, it is one of the most challenging areas. He is often uncooperative and easily erupts emotionally. It's like walking on eggshells all the time, wondering what will be the next trigger.
We don't allow him to have food in his room, but I have found wrappers and crumbs from things he has taken without permission. I try to clean up his space when he's not home. Otherwise, I might set him off by moving something or tossing things out.
It is really hard to endure this as a parent - physically and emotionally. When a child's disability is directed at me or at my property, I struggle to remain patient and positive. Some days are better than others.
If you've read the Explosive Child book, you may conclude that room cleaning is not something worthy of a possible meltdown. Prevention could be better by removing things that he could destroy (as much as possible), and encouraging him to find less destructive ways to deal with frustration and neurological sensitivity.
I hope this helps. I know there is no magic bullet, but you've got friends here.