With this fridge, a RML-8330 (as per wincrasher65), I wonder about another option, although it does take precious freezer space: A few hard-sided freezer packs, such as what Rubbermaid sells. Keep 1-2 in the freezer part, then before a trip, just turn the fridge to 12 volts and move the packs to the fridge part.
As previously stated, one downside of this fridge is that it is tall and narrow. I wonder about two Valterra fridge fans (both use two "D" cells, and the batteries last about 4-6 weeks in constant use) mainly to keep air circulating. They do not move that large a volume of air... but enough to help with cooling such a tall, narrow space.
I didn't see an inverter with the Travato, but looking at the blog on another post, I -think- I can mount at least a 300 watt Morningstar SureSine inverter underneath the bench seat, then mount a receptacle nearby. With such a small battery, I'd not want to go more than 300 watts anyway. However, it is enough wattage so I can charge things overnight (a power tool battery, laptop, etc.) without having to fire up a generator.