My system is much more primitive than the dude's and I don't tune with AI. But FWIW I've been using a simple float switch in the tank that lights up a red LED on my gauge pod. Used an old lighted switch that had been unused from "the fan mod" days to shut my pump off if it goes dry.
It works.

 

Just wondering if Brent still produces these kits? If so, I'll probably pick one up in the coming months.

 

Still there on his website:

Mechanical Pre-Turbo Water Injection - Wannaspeed

 

Yes sir still do. Drop me an email and we'll talk about your setup and work on a system for ya. Brent@wannaspeed.com