Somebody should invent a bumper mounting bolt that instead of the round head of a carriage bolt, has a stud sticking out. Slip the beam of the Hi-Lift over the stud, wing-nut it down, and away you go!
Actually, you could do the same thing to the face of the bumper. Easy peasy if you have the extra holes in the face for the bumperettes.
A carriage bolt inserted from the back, nut it down to the bumper, then use the remaining thread to anchor the Hi-Lift.
You'd probably want to use a longer than expected bolt and have a second nut to act as an adjustable spacer so you can pull the jack beam away from the bumper to allow for the thickness of the mechanism.
Never done it, but should work.
Paul