First thing you need to find is an awesome welder, not just a good welder, but an awesome one. I am talking about a person not a machine. You can go to Harbor Freight and but a machine that will do the job, The person to operate that machine will be a bit harder to find.
I would absolutely love to have a short bed dually. Yes Ford actually build them for the Railroad. I saw one on the road recently, they look awesome.