I decided against the dual odyssey battery setup. There were a number of reasons... The Odyssey 1400 would get run down after 12hrs with the ARB Fridge. I want the fridge to be able to run 24-48hrs without killing the battery. The added wiring complexity and possibility of causing warranty issues if the charging system failed. The cost of doing the dual battery system (additional battery, wiring, battery management, battery holder).
Group 31 was the biggest, highest reserve capacity battery I could find that could fit. Originally, I was looking at the Odyssey 31M-PC2150 (over $400). Specs: Reserve Capacity 205 min, CCA 1150. Then I found the Sears Diehard (exact same specs and size - manufactured at the same plant as Odyssey) for $255. It was in stock at Sears (vs shipping the Odyssey) and they would replace it (no prorate) within the first 3yrs. Here's how it looks...
Cam-Shaft (Cameron) wired up the battery & accessory block. Finally, the wiring is cleaned up.
Battery fits in the factory location (barely). Used the factory tie down but had to replace one J hook due to the increased battery height.
Here is my backup/dual battery solution. It's more universal and simple. It has a nice accessory charging outlet and handy for helping people with dead batteries.
Schumacher's PSJ-2212 ProSeries Jump Starter/Portable Power Unit has 2200 peak amps, 330 cranking amps and 275 cold cranking amps. This is a power source for all 12 Volt DC accessories that are equipped with a 12 Volt accessory plug.