I can't listen to it right now, but from looking at the score....
You might as well have two separate staffs for cello and viola if you're having them divisi the whole time anyway. On a similar note, having that much divisi in the first place might not be a good idea, unless you deliberately want a thin texture. A junior high string orchestra probably won't have more than 6 cellos and even fewer violas. Maybe simplify or revoice the chords from the guitar.
Giving the basses an independent part also probably won't work well, and while it doubled/octaved cello some of the time, the resonance would drop out the times it isn't.
The triple stop in m. 19 in the second violins looks dangerous, especially for a young player, but I'm not exactly a string player myself so yeah....