My truck is totally stock. I have an Auto Meter EGR that is independent of the computers. I want to see the real temps in the exhaust ports, not what the computer "thinks" the temps are. You are betting your engine in this gauge. I ran the same thing in my KW.
You can thread the cast iron Exhaust Manifold to receive the temp probe. No welding needed. You want the probe to be as close to the exhaust valve as possible.
I admit that I do need to add one for monitoring egt while towing. as far as cool down, when I stop I shut down the motor, exit, lock the doors and use my remote start to restart the motor. It runs for 15 minutes then shuts down.