In theory you can just keep testing until you find the right level. It takes a bit of self-advocacy, but in my experience, USAFA will look at your results and keep offering placement tests until you meet your match.
For me, this meant I tested all the way out of calc 1,2 and 3 and straight into differential equations. Because I knew I was majoring in something technical like physics or math, and I felt my calc 3 knowledge was a bit shaky, I opted to start with honors calc 3 instead of diff eq. It was definitely the right choice. I learned a ton in that class and it was great to have a challenging class with other 4 degrees (when I was in several other classes with upper classmen).
Major matters as well - only a few majors (Some engineering majors, math, physics) require linear algebra. It may be worth looking at what majors she is interested and their math requirements. Linear algebra is a great class if taught correctly, but I have seen quite the spread of linear algebra classes. Spending 4 pages manipulating a matrix into the identity matrix? Maybe not the best use of time. Learning what that means and how to apply linear algebra to real problems- much more useful.