I have a 19 foot starcraft superfisherman. I have 3 batteries. Two up front for the trolling motor, and pumps. The motor battery is also connected to the am/fm radio. I want to add a marine radio, docking lights, and may need power to use submersable water lights for night fishing. I dont want to get stranded on the water, so should I get a fourth battery? And how should I hook up that fourth battery? Im courious how the other boat owners power all the accessories? Thanks