my neighbors' backyard abuts and is 3 feet above mine. When I moved in I planted arbutus unedo along the top of that 3 foot wall. Now they are huge and beautiful but getting leggy and bare at the bottom and providing less privacy. I want to plant an understory shrub or something among them. Someone recommended Lonicera Nitida "Red Tips." It's pretty shady, dense clay soil under there with some morning and afternoon light.