Convenient +12v in engine compartment?

I'd like to mod my fog light relay to activate whenever the car is powered.

Try 1: A jumper across the relay contacts won't work; that's hot even with the car powered off, so the lights would be on all the time. Strike one.

Try 2: Ground the low side of the relay coil, instead of having the combo light switch do so. But the 12v feed to the relay coil is only hot when the taillights are lit (i.e. headlights or parking lights are on.) Strike two.

What I want: A 12v line, in the engine compartment, that's only hot when the car is powered. Ideally, only in Ready mode, but I'll take Ign-On mode too. I'd like the line to be easy to tap. It only has to drive the relay coil.

(I could probably find this inside the relay box, but that looks like a pain to work on.)

With this 12v feed, I can rewire the relay coil to take the "ready-hot" 12v line and a permanent ground. The fogs will light when the car is ready, regardless of the headlights.

Edit: I found my answer; another post will document the "Cheap Fog-DRL mod."