Just as a data point - we've had the mobicool fridge, got it at a good price and while its spec'd up to a fridge/freezer, we've mostly run it as a fridge and it works out quite nicely. On a single 110AH battery, top'd up at home, we spent 14 days on the road, with a few 2 day stops where the truck didnt move at all. And we never had a problem with power. Avg driving on days we were driving was about 2 hrs to 3 hrs. and weather was mostly mild with temp between 22 and 35 deg C.
It also runs 24/7 here at home, as my beer fridge in the 'office', when we are not on the move. and is often pulled out back into the garden during the summers ( since it can also do 230v ) for bbq's and when just generally spending a day out back.