Yesterday I had a bunch of driving, 100 miles, (60 which was highway) and decided to try some engine off coasting. Was able to boost the trip milage by 4.0 MPG with 8 mile of engine off. With the aero mods the coasting is really good and I had several places where the coast was better than .5 miles.
But as you know the scangauge dies and you have to mess with the key. I was thinking that if I went into the coil pack power supply(sounds like the same thing you did) I could kill the engine with out losing the scangauge data. So I'll try a tank with the coasting and if the transmission doesn't complain my plan is a kill switch and push button starter using SVOboy DIY.