Look up the Andersen fifth wheel setup. It might work with your current gooseneck, and if you have a 2" ball made for it, it will do what you want.
I have a b&w gooseneck and got the companion adapter and just made mine a real fifth wheel like it should have been, anyway.
I lengthened the hitch while I was at it, so the tailgate can be opened and closed while hitched up. The two step process was a recipe for disaster, IMHO.
The bonus of the Andersen or b&w setup is not having rails left behind when the hitch is removed.
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