I just love these stories, man!!
We had something similar when I was young. Also a black-hills adventure. High School days. Before we drove out I asked my brother if he had a spare car key to bring with ...just in case (we locked ourselves once before). He did and he somehow set it on the top of the car's rear quarter by the C-pillar and forgot about it during the packing, etc. Back in those days there was a horizontal ledge in that region of the quarter panel. Well we drove out there (~900 mi), went all over the place, different hotels, sightseeing, hit some bars/casino's, etc. Had a good time. Couple days after we were out there he asked if I had that key (that he set on the rear quarter for me)? I didn't know anything about it. He got all mad but soon after we stopped for gas and looked on the quarter panel and it was STILL there! We still laugh about it. Same thing, nobody bothered the key or the car....
Maybe that's a good strategy for the OP, just put a cheap, generic (unprogrammed) fob outside your truck door....