I just answered a question similar to this one. I have only heard of one case in which someone was able to shadow/intern for a stage manager on the tour, but she already was on the tour when the opportunity to shadow arose. I’ll also add that there wasn’t an opportunity or opening until she worked her ass off to make that happen for herself. The people who work in backline, sound, stage managing or techs who are on the tour have many years of experience. Here’s my advice:
Make live sound a “long-term” goal (within the next 10-15 years). Make getting on Warped a short-term goal (meaning within the next 4-5 years). That means getting any job you possibly can on Warped. Think about how hard it is to get just any job in general out there…let alone something specific like sound. Start broad, and take any experience you can get. Volunteer at Warped until you can get a job on the tour whether it is merch for a band, working with non-profits, or anything else. Later on, leverage your contacts to specify your experience and knowledge.
In terms of being a girl, honestly in my opinion it’s not even worth thinking about. Worrying about not getting treated the same because you are a girl in the industry is just a waste of time. It’s going to happen here and there but there’s not much you can do besides stick up for yourself, stay professional at all times and continue to prove everyone wrong.