I had the same concern, so I installed a Blue Sea Systems add a battery dual switch along with a second battery I purchased from Autozone. Couldn’t be happier. I was worried it was going to be a pain in the butt to install, but it was fairly straight forward. For less than $200, it is worth the piece of mind knowing you won’t be stranded and it requires no brains after you install. You don’t have to switch anything back and forth. It uses one battery for music if you hook it up that way and won’t touch your other battery that you use to start the boat. Love it and I’m not even affiliated with them.