Texas Transportation Code Sec. 502.409(a)(7) prohibits a person from attaching or displaying a license plate that alters or obscures the letters or numbers of the license plate, but Sec. 502.409(c)(5) creates an exception for a bicycle rack that is attached to a vehicle in a normal or customary manner.
Know of any good bike racks?
In other words, a properly chosen and placed bike rack could legally completely cover the rear license plate.