As many know, the gmt 400 OBD2 big block trucks suffer really bad from heat soak. Sit at a stop light a couple times in the summer and IATs skyrocket and power goes way down.

I have a water Meth kit, to aid in this, the problem is I only need it to come on when IATs are above something like say 120? It can tie in to the MAF or the MAP. I had it hooked up to the MAP, but towing I was at too low of vacuum and it sprayed too often.
I was thinking I could have more control and spray less with it connected to the MAF, as the MAF can read more airflow than I flow WOT.

Also when I used it before, I didn't have the IAT, where it was cooled by the water Inj.

Planning this out better, I'd like it to come on during heat soak, and very little spray, the controller is variable.
My thoughts for temp engagement is to use an e-fan controller that powers the unit on. I could locate the sensing bulb touching the intake.

Before any replies, I know these water Meth units are usually only used on forced induction and mostly diesel. I don't plan to run meth, only distilled water.

Anybody have any thoughts?
Let me know what you think. If I get to it before I go out of town again I'll report my experience.

Any tips are welcomed.