You've got all day, you'll probably be safer parking in the grass just before the pavement lot.
If you drive up the auto road and park at the summit, you have to leave before closing time or they close the date, lockimg you in. However, if you let them know before you drive up, you can leave your vehicle overnight on the summit and drive down the next day. You could spend the night at the lake of the clouds hut.
During the summer they close the gates around 8:30 so park out side the gates. Winter hours I don't know what time they close the gates.
I think the gate closes at 6
You can stay up there and go hiking around the summit but you have to be down the base before 8 30 PM. That's when they close the gate.
Yes you can park at top. And hike from top. They do have a gate at the front, so I'm not sure if you have to be out at a specific time.
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