thinking of planting a privet hedge in my backyard to keep my neighbors from using my lawn as walkway from their house to the alley out back. Would like an "L" shape hedge. One side is apprx. 11 feet and the other would side, I would just plant the remaining plants I get. Question is- what would the spacing be to obtain a thick full hedge. Type I'm looking at is Ligustrum amurense and recommended at 18"-24" spacing. I also thought about a barberry bush hedge (to stick them where it might hurt if they decide to walk through it). What do you think of the barberry?