I wonder if the resistor can be put on the track side sizing it to reduce the trip margin. That would be an easy install. Only one resistor would be required, as opposed to one per trolley.
I think that could work!
I suppose the penalty is you'd always be drawing power even when the trolley is not in the stop section. This constant power draw would "pre-heat" the thermostatic NiChrome resistor/switch which would affect the stop-timing range though probably not consequential.