If you are not using the Load terminal, battery life setting doesn't matter. It's not easy to use the Load terminal in an FWC - you need to disconnect the positive wire from the battery to the FWC fuse block switch and instead run a wire from the Load terminal to the fuse block switch. And I think you also need to rewire the 120V-12V Iota converter. If you are able to pull this off, the Victron MPPT will protect your battery by disconnecting the load (all your 12 V devices) when the battery reaches a set low state of charge, 50%, 30%, etc.
