Looking for something that is going to last at a rural farm. The sign will be 4' x 6' and slide into slotted 4" x 4" posts. The sign will have a routed shape. I am looking at possibly using 1/2" thick Luster Board or Nu Alum, but I am concerned that the wood edges will start to pose a problem. Would sealing the edges with 3M edge sealer be the way to go, or is there another product that would be a better edge sealer for this application. If it was just a rectangular shape, I would probably use edge cap. I thought about using 6mm Dibond material, but am concerned that it will not do well in the wind without any horizontal supports. Any advice?