12v cig lighter socket to the controller load terminal?

What is the amp draw of the fridge? What is the max output (in amps) of the Victron? As long as the Victron can output enough amperage to power the fridge it should be OK.

The problem is going to be when it gets dark/cloudy...when there is no solar output there is no power for the Victron to supply. I would wire the fridge to the battery bank so you have guaranteed uninterrupted power, then let the Victron charge the batteries as solar is available. You don't gain anything wiring the fridge directly to the solar controller.