I'm not familiar with the term "marching refrigerator" - what is it?connect a marching refrigerator
It is much more efficient to connect your devices directly to 12V rather than going through an inverter. You can buy 12V charging adapters for all sorts of mobile products be it phones, laptops, iPads (maybe?) etc.. All my devices use 12V except for an inductive cooktop, toaster and kettle that I use on extended trips in the ute.
In the Foz I run a 50 litre 12V fridge and a 300W inverter off an aux 100 amp hour battery.
In my ute I run a 110 litre fridge/freezer and a 3000W inverter off 2 x 110 amp hour batteries.