Had a young driver call me in a panic this summer. He had locked his keys in the back; went to him and had the bulkhead door open in less than 3 minutes using (wait for it) a lottery scratch off card.
OK OK, I will tell (re-tell) my one mistake with keys:
Once as a young cover driver, I was sent out blind with a million air stops. AT MY FIRST STOP, I grabbed my keys, stuck one in the bulkhead door and turned it. It instantly broke off in the lock, BECAUSE.......wait for it......
It was the overhead door key. Now I had no way into the back of my truck! I didn't have a scratch card, but I borrowed some tools and was able to break in.
When I later got my own route, and the trucks started having the same key open both doors, I would keep a spare tucked away in the wiring above the windshield.