Goose neck, 5th wheel connection, Long bed, short bed truck

I agree with most here, a fiver that heavy is well into Dually country unless you want to be over truck ratings.
Cargo capacity of any truck is reduced by EVERYTHING in the truck - passengers, hitch, tools, the dog, auxiliary gas tank etc.... well, I'm sure you get the picture.
You are probably going to need close to 5000# of payload unless you plan to drive an empty truck solo.
And no way on a gooseneck for a fiver. Frames are not designed to take that stress.