Just installed a small Boss Bluetooth system which is wired directly to the battery. I also installed a switch so hopefully I don’t accidentally leave it on for days/weeks. I also want to add a small Garmin GPS/fishfinder. Knowing how small these batteries are maybe isn’t meant to additional electronics on for a long time, 1. Do people add a dual battery set up similar to a boat? 2. Is the alternator strong enough to charge both batteries at the same time? 3. Is there a larger battery/dual purpose/deep cycle battery for this purpose? Thanks in advance.