I installed the plates on the car.
On the front, that plate is just held in with two screws, in such a way that it bends just a little, and covers part of the old radiator lower air intake.
I know...... I don't drive this car very fast, but I still can't NOT take aerodynamics into consideration. Curved to match the bumper just looks better than flat!
Anyways, I might make some sort of a custom front mount that holds the plate and fills in the guppy mouth. That whole thing would then be removable for when the tow bar is in place.