Not sure if any of them would work right with a williams reverse unit. When power is removed it will resume forward when restarted. A mechanical E unit has memory after power is removed. It could be done I think if there is a button to re orient it when power is restored and stops are not too long. If The E unit is removed and track power is done with DC,it can be done with relays,I think. I do not have one of the trolleys so I am not sure of the nature of the E unit,if it is the same they use on engines.
Dale H