I hope that by reading all the posts and trying to sort out fact from urban legend, you have decided it is what you need, not what other folks (including me)think you need.
Some old urban legend for needing a long box:
Longer wheel base. You have to look at the brochures on the trucks. A crew cab may have just as long a wheel base as some long beds.
Larger fuel tank. Maybe. It now depends on the vehicle. my short box F250 has the biggest gas tank available for Super Duties.
Hauling a sheet of plywood. Now there is some real urban legend. What is wrong with flopp0ing the tail gate down, putting your 8 foot lumber in there, strapping it down and hitting the road?
Knocking the back window out. Fifth wheels with the new styled nose work just fine with the extended pin box on short beds without sliders
hauling "stuff" when gong camping. I don't have things like golf carts, snow mobiles, or whatever, so a long box is not needed.
I could go on and on. However i hope I have given you thought enough to get out there and pick up the literature and get what you want that fits your specific needs.
I could go on and on, but am tired knocking on this key board with my fat fingers.
Personally I drive a short box, crew cab, F250 with aux fuel tank in the bed and a non slider Reese hitch, but that darn sure does not mean that is what you need.