As a retired firefighter, I have put out lots of vehicular fires and it does not matter how quickly you get to the fire, it normally is better to let it burn and get a new truck instead of having to fix many things such as wire harnesses. Leaving ghosts in the system for life.Good info! What are you looking for under the hood? Are you just looking for signs of leaks?
FWIW, I carry a big fire extinguisher too, but it's in the bed. I think I'm going to have to find a place to hard mount mine inside the cab.