DIY Car Dashcam w/ Raspberry Pi on off switch

I am planning on building a dashcam with a raspberry pi. The plan is to have the RPi connected to a battery or fuse connection for constant power and to use the ignition line as an input for a relay to toggle the unit on and off. This is so the card does not become corrupted from improper shutdown.

The RPi has 2 pins when shorted allow this to happen. I have found a tutorial on coding and it states to use a momentary switch to short the pins. Short the pins on, short the pins off.

What I would like to do is make a relay to short the pins momentarily when the ignition is on, and short them again when the ignition is turned off. I was looking at the wiring diagrams on this site and found momentary action, but am I able to do this when input is applied and disconnected?

Any help is greatly appreciated!

Additionally I have reviewed the following pages:

Momentary Positive Output when Positive Switch Turned Off
Constant to Momentary Output - Positive Input/Positive Output

But I still cannot figure out a way to get the action of both, if it is even possible.