I recently bought a parts truck and it has one of these on it. It's a Texas dealership but I live in PA so this truck has seen the USA I guess.
Too bad mine is rotted on the top or I'd be selling it.
I was told these were actually aftermarket bumpers the dealers bought and put on if the customer requested. Also told many trucks didn't have a rear bumper from the factory and this is why they would add these.
This is the first one here in PA that I seen. It must not have been done here or at least, not often.