My parents never opposed my trips, but they did happen to show up several times, at state campgrounds they knew i'd be at, around lunchtime. Now i'm just the odd son who bike tours. No big deal.

My advice : Finish high school. Get job(s). Start university far from home. Tour on Breaks. Cut the cord.
I really like Machka's approach of teaching, possibly overseas. Great career choice. I'm looking into it as a career choice for myself.
Your parents will come around to your way of thinking eventually. Soon she'll be bragging to her friends about her college student son who's out traveling the country.

(Gap year is an idea that really needs to catch on in america. too many helicopter parents.)