You're going to need a charge on the way up.
I've done a somewhat similar distance (45-50mi up a mountain at speeds ranging from 35-55 mph) but only climbed ~3000ft and arrived at the charging spot not far above LBW - you're doing ~6000ft which means you need to save about 4.5 kWh over 50 miles or about 90 Wh/mi.
45 mph is about 170 Wh/mi on flat ground (5.9 mi/kWh according to range chart) - optimal speed is around 12 mph around 12 mi/kWh which should be around 80-90 Wh/mi, you're going to have to do that to have a chance.
On the other hand,
abasile lives up that road and his
charging station is available to use - contact him and stop by while you charge enough to make it the rest of the way!