There are some great responses here.
I agree that the chosen boarding high school is just out of realistic reach for OP.
What does seem within reach is to enhance the high school academics where they are with online, community college courses, studying on her own, etc., while using the ranch-type resources locally to learn management and horse-related everything. It’s also true that having your own horse at home is likely to give you more saddle time than at school. It’s also a good idea to ride/experience many horses. Look beyond the hunter/jumper world for these experiences.
You say you want to make connections in the horse world unavailable in your area. Wouldn’t it make more sense to make those connections closer to the time you’ll be needing/using them?
Going to college is probably a pretty good idea, whether you choose a career in the horse world or not. A degree or coursework in an accessible, well-paying profession can serve you well in any case. Even horse professionals can get injured or age out of such a physically demanding profession, and some just decide to do other work.
As you’ll find in this and other threads over and over, many folks choose to get established in a financially secure position before taking up horses after school. That’s how I did it – master’s degree, internship, temporary position that turned permanent, share-boarding to reconnect with the horse world, then a fixer-upper horse that could do (and had done) everything I wanted.
So many more options than you’ve encountered in your young life! Spend a bit of time reading these threads and you’ll learn so much – from people who have done it. And don’t discount your parents and school counselors as sources of experience, either.
Good luck!