Most fifth wheel hitches are made to be removeable from base rails, using pins. PullRite base rail is square, a half inch higher than Reese. Advantage is less slippage than Reese, but the disadvantage is a higher silhoutte. Some newer trucks have higher platform, but lower sides. Fifth wheel mounting brackets are intended to make sure the weight of the fiver is on the frame, and not the bed of the truck.
PullRite brackets are slightly more expensive, but are made to bolt to existing holes in the frame.
So installation costs can be less. Short box hitches. RVers often want bigger, heavier trailers but shorter wheelbase trucks, which they like better when not towing. The hitch is on rails. You can pull the pins, slide the hitch back, turn a sharp corner whle parking, and then put it back for highway driving.