My dd is a plebe this year, so I can't yet speak about opportunities after WP, but I can pass on a few of the things that she's told me about WP.
Your question asks, "DO the women have a difficult time at WP?"
My answer is yes, but so do the guys. West Point is a rigorous program that challenges these young people continually. That's what it's meant to do, and it does. Some cadets are better in athletics, while others are better in academics. So, a cadet will most likely have a difficult time in some area, some time over the 4 years.
I'll break things down a little more. Academically, there is very little difference. The difference is determined by the major the cadet chooses, not by gender. There are a few differences in PE classes; the men take boxing, while the girls take combatives.
Athletically, all the cadets are required to participate in athletics. For the APFT (Army Physical Fitness Test) the women do have different standards than the men, based on the differences in body type/structure.
Keeping in mind that West Point is approx. 15% female, it may seem like the women may have problems dealing with the men or be discriminated against. My daughter has not told me of any issues that she's had. She has 2 older brothers, and has been involved in male-dominated clubs/sports in middle and high school, so West Point's environment has not been much of an adjustment for her. During the Plebe review/parade for PPW, I saw a prominent presence of females in the upper positions within the regiments. Whether it was more than 15%, I don't know.
Last Aug., during Reorgy Week when we could IM, I asked how the guys were treating her. She said that they've been great. That if it wasn't for a few of them, she wouldn't have been able to get through all her Rucks; they were a huge help. One rainy cool morning during Beast, all the new cadets were wet and cold, but she and another girl in their squad were visibly shivering, and my d's hands were going numb. Her squad formed a huddle for warmth, and put her and another female new cadet in the middle because they were the coldest and bluest (her words).
I met one of the young men from her Beast squad during A-Day weekend, and another one during PPW. Wonderful young men. My impression is that if the girls don't expect special treatment, and they are working their butts off, then the guys will help them. Some of the guys do look after the girls better than others, though. Beast is a very equalizing experience. They, both males and females, are all helping each other get through.
The one thing she has mentioned is that there are a few girls that are boy crazy and that works against them. She says it's easy to get a bad reputation, and the guys don't respect them much then.
When I was there in Oct. for PPW, she said she loves it and she belongs there. I don't think she'd say that if she was surrounded by male chauvinism. That always pissed her off in high school. But she also knows how to get along and be comfortable with boys.
If your daughter is willing to work hard and not whine or quit, then she should be fine at WP and the sky is the limit for her. I would suggest that she get involved in the clubs/sports they offer. The clubs are a way for the plebes to fraternize in an acceptable forum with the upperclassmen. My d joined the rugby team, and I think it helped her work off/run off some of the stress from everything else while being a part of a very close-knit group that provides a lot of support.
If you have any other questions, feel free to ask or PM me.