If the goal is for the woman to simply finish within the time limit on each stage, then the flat stages should be no problem, she can shelter in the bunch so absent bad luck w/ a mechnical etc she can finish with the bunch. The challenge will be on the mountain stages and the time trials.
For the mountain stages, the woman will need enough watt/kg to keep up with the grupetto. See here for W/Kg of men vs women
Power-to-Weight Ratios: Bicycling Training | Bicycling Magazine
It suggests that the very best world tour-class pro woman has FT W/kg similar to the worst world tour men. So, with some drafting on the less steep grades, maybe she can hang with the grupetto.
The ITT might be too tough. Compare men's and women's speeds at the 2012 Olympic time trial. Men's course was 27 miles, best time 50 minutes (32.4 mph), worst time 59 min (27.5 mph). Women's course was 18 miles, best time 37 minutes (29.2 mph), worst time 42 min (25.7 mph). So the best woman, over a course a third shorter than the men's course, did a speed about 1.7 mph faster than the worst man. Over the full men's course, I am skeptical if she could even match the worst man's speed. So the question is, where is the time cutoff?
And then the TTT, if there is one. If the woman gets dropped early, can she continue solo to beat the time cutoff? Or will it be like poor Ted King in the 2013 TdF?
I believe the cutoff time is 1.25 times the time of the winner.
That is makeable.
IF the peloton favors a woman riding the tour one could finish and stay within the time limits. If not there is no way. The men ride hard on a flat stage and any wheel she tries to hold tries to drop her. She is toast.
Normally the guys off the back are all allies trying to beat the time limit. That would not be the case for anyone who the riders feel does not belong. And my gut feel is any female rider who gets an invite just for publicity (or anyone else who gets it for the same reason) would be someone the riders feel does not belong.