Motorhomes generally have a vertical rear wall.
To get the clearance right we need the distance from the back wall to the centre of the hitch pin hole.
HIGH LIFT BARS:
High Lift bars are for Motorhomes with a lot of overhang to avoid dragging out of driveways etc.
If the bottom of your receiver tube is only 300-350 off the ground you will need a High Lift.
Most find a 100 lift gives enough clearance and is still easy to load the bike.