Today I worked on moving circuits onto the second battery so that I can flatten one and still be able to start the car.
It went pretty straight forward. I started by tracing circuits that wanted moved from the component back to the battery, then following anything that tapped into the wires as I went.
This is what the relevant part of the circuit looked like before I changed anything.
And after a days work.
Tomorrow I need to add a switch to the light again because pulling the fuse to turn it on and off is worse than a switch in the cab.