I just planted 3 Natchez White crepe myrtles in a semi-circle framing the front corner of our yard. We live across from a new elementary school in northern Virginia. Need shielding but not a full screen from the school. I was hoping to put small boxwood between the crepes, but they won't get tall enough to help shield our view. Any thighs on taller evergreens that could go between or behind the crepes to help? Want to expand the bed a the way across the front of the house with a mix of evergreen and deciduous now or on the future, but this was my starting point. Crepes are 12' apart.