Sure, bumper pulls get steered a tiny bit to the outside because the rear bumper moves at first away from the turn direction. But it's a difference that becomes smaller as your trailer gets longer.
Even so, a bumper pull does not truly track behind the tow vehicle as some have indicated. Even a short 6x10 single axle trailer tracks inside the turn, despite the advantage of the bumper moving away from the turn direction. If you don't believe me take one through the drive through window at a McDonalds that has an 8' lane, with curbing on both sides and a tight radius. You WILL drag the inside trailer tire up over the curb.
I'm not arguing for or against either type of trailer. Just want to dispel the myth that somehow a bumper pull truly tracks with the towing vehicle. A friend of mine - driving my truck with my 29' bumper pull boat trailer behind it - used the fender of the trailer to take out a bricked gate post because he believed that myth.
xtn