Where do the hikers park their vehicle after Nov 1 and what is the best way to get to Whitney Portal to start hiking at 3:00 AM?

Park at the trail head.

Theoretically parking restrictions continue until the road construction is over -- the contract calls for completion by Nov 7. But I cannot imagine any time would be spent on parking enforcement after Nov 1.

You are still required to pick up a permit to hike (available to all, no quota). So I would ask the people about parking. You might call the Wilderness Permit Office to get a night-drop permit (if you want that) and ask them -- 760-873-2483