Sorry you have to smash your new truck. Must have been difficult & unpleasant.
I added a <standard, known to me> 5 digit code to my remote entry so I don't have to try to remember the OEM code. I also got a scribe and scratched the OEM code in the rubber on the outside, with extra digits on both ends. I keep an extra set of key/fob hidden inside the vehickel. I have the code in my wallet. This is all in case I lose my keys and wallet while on vacation far away from home. I've tested the procedure to make sure it works. I'm not sure what I'd do if that happened and the battery died but I guess I would use the rock method and that not real likely.
I was thinking about a key underneath but if you lock with fob and open with key, the security feature wont let you start vehicle.