Your riggers are minimal draw, and they are not spinning all day long, so your boats charging system will recover any batter drain quickly. The AP really doesnt draw much power either. Radar, Inverters, water pumps, and things that make heat are what will kill your batterys faster than your charging system can recover. I'm assuming you are trolling(i.e. motor running) while you are using these devices, correct? You are probably fine with a two dual purpose battery switched bank.