John - what group/size batteries are those? I am going to copy your idea when I get solar panels. On early model PCs it’s simple to run the wires down through the rooftop mounted refrigerator vent directly into the battery box.
CalCruiser, they are Group 27 batteries. Lifeline AGM 100 amp hrs each. They are identical in dimensions to the Interstate flooded cell battery I took out. The battery tray is attached with about 8 screws so it was easy to remove.
As you know, the location of the power distribution panel under the fridge, and the batteries essentially beside the fridge under the wardrobe, makes it ideal for running cables from solar panels down through the fridge vent. No holes to drill in the roof!
What solar panels are you considering? I’ve been looking at a package from Renogy that includes 2 160 watt flexible panels, charge controller, and all the wiring.