Why not check with the best female rider in the area?
Look up Moksha Jetly, she rode that whole route in record time, is very nice and operates out of Manali which is also a very nice place. You'll need to spend a day or two there to acclimate unless you already live at 4000+ ft. Starting from there will put you just a bit before Rohtang and where you have access to print the permit, you have to have it printed so a local agent is a good help.
Have a great trip it will be very rewarding!
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