I have the Race Face T3 pad and it'll carry 2 bikes. The inner surface won't scratch the exterior, but you have to make sure the tailgate is clean before you install it. Also, if you have rear parking assist it needs to be turned off when bikes are carried over the tailgate.
I had felt the same at first with my new 25 Lariat, but when I pull up the camera and switch to the side views, I see it's dead center in the lane. I suspect that I've been accustomed to hugging the left side of the lane in my previous car which didn't have any driver assist tech.