2008 F-250 diesel CrewCab shorty 4x4 has a GCWR of 23,000 pounds and a GVWR of 9,800 pounds.
GVWR is your problem. If you have nothing in your truck but a hitch, a skinny driver, and a full tank of fuel, your wet and loaded pickup will probably weigh around 8,000 pounds before you tie onto the trailer. That leaves only 1,800 pounds for hitch weight before you exceed the GVWR of your pickup. 1,800 pounds of hitch weight on a gooseneck trailer with 18 percent hitch weight is a trailer with a max wet and loaded weight around 10,000 pounds.
So you're going to be overloaded with any trailer that will safely haul a 9,500 pound tractor.
But ignoring that, let's consider three different trailers that might meet your needs. I'll use BigTex Trailers as the examples, because they have a factory about 30 miles down the superslab from me.
Here are the three trailers. They all are available with 102" width and 20' (or longer) deck plus 5' dovetail. And two of them have an optional 6' deck on the neck (good place to haul the extra dually tractor tires):
14GN/PH Tandem Axle Gooseneck Trailer
The 14GN is the least expensive and with the least gvwr at 14,000 pounds. It's a common tandam axle gooseneck trailer with 4 trailer tires. But you'll be right on the verge of being overloaded over the GVWR of the trailer with a 9,500 pound tractor on the trailer. I'd want the dealer to guarantee me that the "dry" trailer with any options would not weigh more than 4,500 pounds.
18GN/PH Triple Axle Gooseneck Trailer
The 18GN has about the GVWR you need to be certain you'll never be overloaded with the 9,500 pound payload. But it's a tripple-axle trailer with 6 tires on the ground. Most folks experienced with tripple-axle trailers will warn you to chose something with two axles, not three. The tripple-axle trailers are infamous for dragging tires sideways around sharp turns.
20GN Tandem Dual Axle Gooseneck Trailer
The 20GN is probably overkill for your load, but it has plenty of GVWR without the tripple axles. Instead, is has dual tandam axles, with 8 tires on the ground. It comes with cheap 7.00x16 tires, with the much better ST235/85R16 tires optional at extra cost.
What would I do if I wanted a gooseneck to haul a '9,500 pound payload? I'd probably go for the overkill and get the 20GN. Too much trailer is a lot better than not enough trailer, and I don't want a tripple axle trailer of any kind. But the 20GN is going to weigh more than the 14GN, so you'll be even more overloaded with the 20GN than you would be with the 14GN.
What else might you consider, other than jacking up the F-250 and running an F-350 under it?
Tag trailers have a lot less hitch weight than goosenecks (about 12 percent instead of 18 percent). So if you bought a tag equipment trailer instead of a gooseneck, you could tow a 15,000 pound trailer instead of a 10,000 pound gooseneck without being over the GVWR of the tow vehicle. BigTex has those too, but I'll let you do you own surfing for those.
But a 15k tag trailer means you'll have to replace your receiver with one rated for at least the GVWR of your tag trailer.
