You might check into a large university, they typically have many more opportunities than smaller to mid sized universities. Penn State comes to mind. They have three orchestras a Philharmonic, a Chamber Orchestra and the Campus Orchestra. The Chamber and Philharmonic are by audition only. Because there are so many students the top orchestras typically play at a very high level. D plays viola in the Purdue Philharmonic. They are going to Spain to perform over spring break. Good luck.
http://music.psu.edu/area/orchestras
I realize my second suggestion doesn’t fit your criteria either, however, Case Western Reserve is an excellent school for those who play in orchestras. It’s private, about 4200 undergraduate students and has good financial aid for someone with you stats. Within the university circle is the Cleveland Symphony. It’s outside of your six hour radius but otherwise fits well.