I think that the idea is to be able to separate the letters to allow him to store the letters separately and to aid in the ease of setup since he can set them up one at a time and then connect them together. As for the cat 5 connectors, while they may work ok, you may be better served ordering the weatherproof 3 pin connectors from Ray. They use a heavier connector and once connected, keep the water out and are much less subject to corrosion than Cat5 connectors which were not designed for that type of use. If you decide to go with CAT5, I would also pick up a can of corrosion X and give the connectors a good spray as you connected them.