It is very interesting. The truck in that second photo looks like they did a really nice job on it. I'm guessing they chopped off about 10"?
That's probably not a bad option for someone who already has all the right bed parts for the express box and wants it to look more like a short bed. It would be a shame to buy all the express box parts new, and then proceed to butchering it.
One option that we really haven't talked about much is shortening the wheelbase. In addition to the new bed, it would mean taking an 8" section out of the frame. The driveshaft would need to be shortened, and new brake lines. I haven't gotten up under the truck to see what else might be impacted. In my case, since the frame has already had the ends cut off, I would need to add some length back on the ends.
This might be a viable option for someone who has the equipment and the know-how (not me). I used to know a garage that would go out and find 67-72 longbed fleetside Chevy pickups (cheap) and cut them down to make shortbeds out of them. They looked original when they were done (although it would be unnerving for most people to know that their frame had been sectioned, but hey, we do that with some of the front clip mods anyway).