Dual electric fans, FIRE!

I mean draw the hot from the starter large bolt to get my 12v due to my battery being in trunk. Now I tried to rob power from my dash lights to power the switch however that blew out my dash lights. So I am thinking of going double hot to relay and use the toggle for ground I just found this online, Im a bit worried keeping it hot and relying on the switch to gound it but whats your thoughts, look at the link I posted