That's a good question....how should you configure your setup.
I would recommend that you either test the setup, in a quantitative manner (and this will require access to at least one police LIDAR device) or, alternatively, that you set up a mock setup, yourself.
The former is easy to explain and visualize. With access to police LIDAR, you'll be able to test your setup, mounted in a temporary manner, and optimize the on-vehicle configuration.
However, this is difficult, if not impossible, for the vast majority of us.
The next best thing you can do is to thus mock-up your proposed setup, and try to make educated guesses on where your weak-spots may be.
Given that the Accord of your (and steagall's) generation and MYs have a known specific weak point, I would work towards, specifically, "covering" this weak-spot.
Blinder recommends that no hardpoint - a vehicle's weak-spot - be more than 18 (eighteen) inches from the centerpoint of any of its jammer heads.
I would thus obtain the dimensions of the current Blinder head, mock it up with some cardboard or craft paper, and then, using automotive painter's tape, mock-up an installation, measuring off the critical "18-inch rule" to insure best coverage.
As for the rear, yes, one head is better than none - at least having one head back there will offer you rear center-mass (i.e. plate) protection.....
But you'll want to have two heads back there, to offer better coverage.