I'm not sure, but it concerns me that you have SIs even on what seem like good days. I wish you were free from such scary thoughts to more fully enjoy good days.
Maybe having a plan is not a good idea, because having one may possibly make it easier to make it happen? I don't know. I rather wish that you would develop a plan to seek help in cases where SIs are particularly strong. Have you talked to your psychiatrist and/or a therapist about this topic? I think they should know. They need to help you with this.