Hi Delight and welcome!

I'm glad you decided to step out of lurkerdom and join us!
I'm so sorry you're going through this but, as you'll see from looking around here, you're not alone.
To answer your question -- I'm afraid I don't really have an answer. My H is undiagnosed but I, too, struggle with what to do when there's an outburst. I've yet to find the solution to the "how do I do a time out without triggering him?" question. Sounds like you're already trying the methods that were recommended to me. Hopefully some others will jump in with suggestions.
Since he's aware of his situation and how it works, have you tried talking to him about this during a calm time and trying to come up with a solution together?