The jumper is a good temporary fix but the ARB should get a dedicated wire from the battery. The stock wiring really isn't up to snuff when it comes to powering the fridge long term. I have a 10g wire to a Blue Sea fusebox in the rear of the Rangie for powering the ARB, recharging the GoalZero powerpack and other accessory plugs. I have all the hardware to wire one up in the lr3, but haven't done it yet. Also, don't run your main LR3 battery down to far as it can be fickle with a low battery.
As Zelatore mentioned, the Andersen power plugs are a much better connection and I converted when I installed the fusebox. The Anderson power plugs also connect directly to my GoalZero so works out better for me.