What a great topic. I read up on using diodes a little bit here:
https://www.allaboutcircuits.com/tec...-only-a-diode/ Schottky diodes look like a great way to protect battery powered setups from reverse polarity connections. It's of less use to a 240v setup like mine where the cables can only connect one way, but when you're on battery power it could be super important because of the initial battery connection. Those Schottky diodes look like they would be a very easy solution.