My son has SPD.
The thing that worked most for us was when I stopped looking at it as "discipline" (or lack there of), and started to believe that he was always doing his best. I also grew calmer (modeled what I wanted him to experience), and balanced trying to foresee triggers while not expecting poor reactions to environment. I also really, really tried to stop caring what others might think (you don't mention this in your post, but this was a real problem for me and escalated both my son and I).
DD's started watching the Dog Whisperer, and I realized a lot of what he's talking about is what I did/do with my son.
I'm confident in my leadership and project calm.
My son is finally outgrowing his raging impulsiveness, which has helped immensely. He had SPD and impulsivity, rather than just SPD. This is an important distinction, because SPD has a sensory base, whereas impulsivity in more a thinking issue (executive function/control) and may require different strategies.
Specific strategies that worked for us, in addition to what you've listed (ie sleep, food etc):
-communicate by touch first to bring him to focus, then speak shortly and clearly
-provide sensory input that meets his need (either heavy work or firm back rubs in our case)
-role playing, clear rules and guidelines, debrief, debrief, debrief (but my son's very verbal) because we can learn from this time for the next time (or many times after that!!).
I also took responsiblity when he clearly couldn't (ie "I see you need help stopping that. I will help you." said calmy and with hands to gently guide him away. Executive function is not fully operational with most SPD kids, and they need you to act as their CEO sometimes when they've lost the ability to.
I also used 1-2-3 then time-in. I ONLY used this for the biggies. Time in was with an adult beside him, waiting to talk until he'd regained some control. There's a clear point when there's no higher order thinking happening and there's no point in even trying to communicate (this is when they're crying, manic talking or hyped out etc). I used to try to work through it when he was in this state. Now, I rub his back firmly, sympathize ("that was hard!" or "I know, that hurt!"), and only when he's calmed down attempt to discuss. He always has to make it right, by checking in with the other person (so often his sister).
We started the above at around 3-3.5. I can look back and see steady progress. Now, if I say the word "1" he stops whatever he's doing - because he knows I only use it for the important things and he now has the impulse control. The last time in was last summer while on vacation when he was all out of sorts.
GD reflects the value of meeting a kid where they're at. If you're dealing with a kid whose internal sensory world is chaotic, GD is going to look different than if you're dealing with a kid who's not
swinging from the ceiling