Can car be locked from outside with 2nd key fob?

No I'm pretty sure that won't work when I do have two fobs for three of the four gen twos that I have but if I'm not mistaken when I try to do that it just reverts back to the unlocked state because it realizes the key is in the slot. I'm pretty sure that's right but I'll try and make sure I have both batteries and one of these cars set up and try it But if I'm not mistaken this is what we went through the last time

 

You can use just one fob. Remove the mechanical key from the fob and leave the rest of the fob in the slot. Use the mechanical key to lock the car.

You should get a second fob anyway because if you lose the one fob you have it is a whole lot more expensive and inconvenient to replace it.

For your scenario, get a full-size regular key cut from your mechanical key and attach it to a retractable belt clip that you can carabiner to your belt.

 

I never had a Gen2. But in my Gen3, whenever the spouse accidentally left her key in a jacket or somewhere, and left the car before me, then I was unable to lock it with my fob. I was then trapped in a treasure hunt, unable to leave without securing the car, trying to find where she left her key inside, or until she returned, whichever came first.

And of course, she had many possible places where her fob might be. Almost anywhere except pants pockets.