I think what the OP is looking for information about is the full window graphic. I'm assuming the full window screen type. Decals that are being discussed wont really be affected with the rear window use.
I believe that you would need to install the window graphic 'below' the window wiper. Now I'm not talking about the windshield wiper. I'm talking about the felt part at the bottom of the window itself. This is attached to the lift gate itself. This would be similar to installing window tint. Although, from the outside.