I'm working on a design for a client the will be a mixed shrub border along a 150'+ fence-line. The kicker is, there will be 5 red maples spaced along the fence. So I need to use shrubs that will tolerate the relatively dense shade the trees will eventually create. Problem is, most plants that will tolerate that shade will not tolerate the full sun that they will get for the next few years until the trees get more mature. The plan will call for using 2.5"-3" cal. trees. Any suggestions on dealing with this?