A fifth wheel trailer hitch adapter permitting a fifth-wheel trailer hitch to be mounted outside a truck bed and coupled with a vehicle rear hitch so that neither the adapter nor any portion of a fifth-wheel trailer occupies any portion of the truck bed by including a wheeled L-shaped support frame with a vertical shaft having a telescopic inner shaft therein and a horizontal hitch frame telescopically coupled to the rear hitch, a solid wedge between the vertical shaft and the hitch frame, and a plate attached to the inner shaft by a plurality of braces to ensure structural integrity. The fifth-wheel trailer hitch mounts to a base attached atop the plate.