Keep in mind that the OP is purchasing a 2021 Keystone product. In recent years, both Lippert (frame manufacturer) and Keystone (RV manufacturer) have stated that the ONLY approved "gooseneck type hitch" that is approved is the Reese Gooseneck. Using an Andersen hitch WILL void the trailer warranty.
Of course, if the warranty is not important to a new owner, then any hitch you like will "do the job quite nicely"....
That said, I have not yet understood why the "OBSESSION" with 90 degree backing capability with fifth wheel owners.... When you consider that EVERY conventional travel trailer owner is limited to about 35 degrees before the front of the trailer CRUSHES the tow vehicle tail lights, and they "back into sites quite nicely".... Why then do fifth wheel owners feel the need to "risk total destruction on their axles, spring hangers, springs and bearings" by insisting on having the ability to "twist the axles out from under a fifth wheel by backing at 90 degree turns ?????
I've not yet figured that out, as much time as I spend trying to come up with even one situation where a travel trailer can get into a spot and a fifth wheel owner "has to back at 90 degrees to get into the same spot"....
ADDED: Now if you're contemplating installing a fifth wheel hitch in a 5' F150 "short bed" or a similar vehicle, then a sliding hitch might be needed just to navigate normal highway intersections.... Of course, all of those truck owner's manuals state the vehicle is not approved for fifth wheel towing, but......