Hey Matt, welcome.
We added a third battery box onto our Safari for extended bush camping, so worth asking Dave/Julian about that.
I have another Deep Cycle Battery in my boat that I put into the third box just for extended trips.
We also added the Hot Water Service for swmbo and resale value, and have to admit it was worth the extra $$$'s in terms of happy wife and even I like not having to heat up pots of water for showers. We tend to only turn it on when needed and boil the kettle to wash up as there is only 2 of us now.
Here's a pic of the pole box with the third cradle sitting on the side of the guard prior to powdercoating and a not so good pic of the 3 behind the toolbox. Wouldn't even know it's there.