Electric fan controller

I have recently re-wired my entire car with a painless harness. I am building a twin 14" 1400cfm. electric fan (9 amp draw ea.) system for the radiator. I am now looking for a thermostatically controlled fan controller. I want to be able to adjust the on/off temps. I am running a 160* high flow thermostate and would like my fans to kick on at 180 and turn off at 170. I would like to have a thread in temp. probe. I plan to have a bung welded to the top of the aluminum radiator tank. I am also considering a fan relay with just a switch to turn them on and off. I already have a switch panel in the dash with an available switch. It would be nice to be able to park the car and leave the fans on in the staging lanes at the track. what have you guys used?