I have a Toyota Matrix toad. It has low bumpers. I got SUPTID and added a extension on my M/H hitch that allowed me to lower the ball about 6". BIG MISTAKE. Got the Toyota on the master tow dolly just fine. taking it off at the campground was a different story. I left my front bumper cover on the dolly as it ripped off dragging down the ramp.
By lowering the M/H hitch by 6" it raised the back end of the dolly by those 6" and the incline of the ramp was too steep.
Having said that the Toyota rear end also has a low bumper. I never had a problem towing it over speed bumps. I've never dragged the rear of the Toyota on the ground. So far, anyway....