Thanks, Chief!! I have a 2017 SLT Terrain, the little brother of the Yukon. I have been pretty careful since getting it to always keep the fob in my pocket, but I can see how a careless moment can get you locked out. Mine has the app that you can load on your smart phone to do all sorts of stuff remotely, including unlock and lock the car, start it, etc. I always keep my iPhone in my shirt pocket, and could always unlock the car with that as well. I do like your idea of the spare key, though. Mine just came with the two fobs and no separate simple key. I'll have to try to remember to have one made, and hide it. Great idea.
Best Regards, Les