After all the stuffing around have you thought about using a water/air inter cooler?
Also, with regard to wiring it up, My suggestion would be to have it hard wired (with fuse etc) and to use an thermo switch... that way it wont be on during say night driving or even at high speed... but on slower 4x4 work or hot days it'll kick in... shouldn't be hard to get a switch like this as most thermo fans run this way...
just place the sensor near the cooler itself..
As for spray over the cooler, you'd need to have a performance chip control this, for any real advantage. The heat soak into the inter cooler happens after the load has been placed on the motor, it therefor affects the next use of the turbo if it is required before it has time to shed the heat...
I'll see if I can find some of the links the ricers use to tune there WRX and Lancers with...
Nah... cant... here's a few...
http://www.freeengineinfo.com/intercooler-1.htmhttp://www.rallysportdirect.com/shop/cu ... -2833.htmlBasically the gist of the article I was looking for covered the time for the heat soak to set in and the best time to cool it and for how long and with how much... Keep searching google if you like... it was one of the more popular hits when I first stumbled on it... Im looking at the glycol/air systems at present.