Timothy Morlok says:

Details West (detailswest.com) carries white metal castings of modern switch motors,SM-903, that mount on the outside the rails.
Central Valley (CVMW.com) has a plastic switch stand kit (6 per) #1604 that could be positioned over the holes on extended switch ties. When you use these, make sure that they are mounted beyond the clearance point for your widest car. If this doesn’t lineup with the tortoise hole use a faux metal plate over the ties between the rail and the switch stand. In real life these plates are used in some locations to keep debris from fouling the throw rod.