Prison Guard position is very similar to Ben Dover, but with the receiver bending over at the waist, but with the receiver's wrists pulled back and held by the giver (as if cuffed together). Bending over pushes the pelvis back against the giver allowing easier and deeper penetration, but is otherwise less intimate than the regular Standing version.
For variation the receiver should try spreading their legs apart or bringing them together. However, the farther the legs are spread the deeper the giver is going to have to squat to gain access; say hello to burning quads. To overcome height differences, the giver should try squatting, or the receiver should be given something to stand on.