Probably is too late but i would take somebody extra non rider in those cars just to have somebody to give you guys water. Why? I wouldnt drink the water from the fountains in the skyline. I dont climb to start with so the two times i been there I needed somebody (wifey) to pass me fresh water kind'a often... or between stops that is around each 3 miles or so...

Enjoy the trip I want to go back there this year.