SPD-driven bullying - at home

Tim is a 5-yr old with a mild to medium form of SPD. He does nicely in school but at home he can be rather tough. His emotions are like a 'jo-jo' and his SPD triggers include things like being told what to do (ie clean up the room, not watch tv anymore, etc), transition from home to school bus or another activity or simply having to stop doing what he wants to do. He then manifests his emotions and dissatisfaction by either punching or hitting his older brother, starting off a fight between them, or by verbally abusing the rest of the family (ie 'i will shoot you', 'you are stupid' etc). He also can switch his sweet side on very shortly thereafter and tell others in the family how much he loves them etc.

Tim attends sensory classes and gets help with fine motor skills among other things in his SPD spectrum. His current therapist believes he needs to find a way to vent out that anger consistently and through various ways.

Some of the things we do with Tim to manage his emotions and related SPD issues are:
a) cutting out sugars and artificial sweeteners/food additives from his diet wherever we can,
b) monitoring energy levels and channeling his anger into sports or just plain play outside
c) trying to validate his feelings and avoid directions but rather explanations on what we want from him and why (mixed success)
d) use of punching bag
e) massaging, stretching and wrestling with Tim to allow for body contact

Time outs for bad behavior have not really worked for Tim and we use them infrequently. We tried with charts for good behaviors, we mixed success at best, and may consider them again.

We would love to hear of any other general ideas on how to deal with emotions/anger management present with kids with (probably) mild to medium form of SPD.