I have 4 "coach" style lamps for the outside of the house - 2 for the front and 2 for the side. The side will be mounted on either side of the door, which is under a porch. The front will be mounted on the front of the porch roof posts (hollow, square posts). The lamps are all to be mounted flush, with holes cut in the hollow posts (front) and the wall (side). My question is this: can I use those round, blue plastic "add on" boxes set in the wall/posts, or do I have to use those metal "waterproof" boxes? I used the "waterproof" boxes on the back of the house and it doesn't look the way I want. The lights stick out away from the wall, and the lamp bases are larger than the boxes, so they don't seal completely anyway. Suggestions? (Also, the "waterproof" boxes are $12 apiece as opposed to the plastic ones which are only a couple of dollars).