Paul -
Have a great trip. I look forward to your updates.
I re-did all my electrical last Fall with striking similarities to yours. I agree that its incredibly time consuming, but so satisfying to flip switches and have reliable power where you need it. My ARB fridge runs stronger with clean no voltage drop power (10ga), as does the dual ARB compressor (same as yours) (2ga).
Question: I run one battery (Group 31 deep cycle Deka Intimidator). Three days parked at OE with ARB fridge, LED's at night, charging phones, drones, and cameras (the latter off the inverter) and started just fine. I am leaning towards one of those small lithium ion packs as the emergency jumpstart source, or a dual battery but the second battery being just there for emergency backup, no loads connected. This should avoid the worst-case scenario where both are dead because accessories on the second ran too long and something from the truck ran down the primary. What would be some disadvantages?