She might have had the duct tape in her purse since she probably used it at the 'anything but clothes party' or it could have been in her car since it was used on the gas cans. Just maybe?
The duct tape was probably in the glove compartment of the car. Since there was no possibility that the tow yard guy saw it there, it was probably removed by one of the A's so as not to cast further suspicion by LE on the beautiful darlin sweetheart.