I have a short wheelbase one ton Dodge diesel. I bought it as a cab and chasis, no box. I had a local welder make me a custom flatdeck, with a U shape. My plate hitch goes onto the frame, in the U, under the level of the deck. When I’m not pulling the trailer, a piece of one inch plywood slides into the U, and it becomes a solid flatdeck. At the time I bought the truck (new, in 1997) the box that I did NOT buy was worth $10,000. The flatdeck I had made cost $2500. These prices obviously have changed since then, but similar savings may be expected.
The problem with a lot of gooseneck trailers these days is that they do NOT fit on newer pickup trucks. The sides of the pick up box are too high. So CHECK this before you make any purchases. With a flat deck, this is not an issue.
The trailer I have now, I just bought used a couple years ago. It’s a 2 horse gooseneck 5th wheel, custom made originally. The reason it was for sale was that the previous owner had a REALLY BAD car accident, and nearly died, and it took several years for her to recover (they didn’t think she would survive, but she did). In the time that she was incapacitated, her husband bought a new pick up truck. (Was it the old pick up truck she was in for the accident… IDK). The horse trailer went into storage for several years. When they went to pick it up again… it would not fit over the high sides of the new pick up truck. Thus, it was for sale. With my flat deck… no problem there.
A plate hitch is the strongest option. My hitch is OLD. We bought it with the previous gooseneck trailer we had, bought that in 1976… and it was OLD then. They don’t make them like this any more. I have people who salivate over my hitch. When we bought the trailer, and the full hitch, a mechanic friend looked at it and said that I could drive off the side of a mountain, hit the rocks below and spin the whole rig around a few times before hitting the rocks below… and that truck and trailer would still be attached together. I’ve never tried this, but there you go. Get a plate hitch.