I'm driving from San Diego to SF, and then on to Portland. I will use evtripplanner.com to calculate RM and stop at all the SuperChargers on the way. But I don't want to overcharge as it takes too long. After calculating the route's RM between SCs using EVTripplanner, what formula between each SC is best for reasonable peace of mind? RM + 50 miles? RM + 25%? Some other formula? Thanks.