When the Fridge kicks in it will drag around 50 Amps for under a second and then settle to around 10-12 amps. The compressor only runs for about 5 mins out of every 20 (I tested mine in warm weather too)
The average consumption is under 3 Amps Average over an hour and this was on a Full size mains fridge with small freezer section. I have pictures somewhere of the battery managment system during a 48hr Test.
Regarding the invertor where is this to be situated?
Heres the fridge set up in the bus that I was building
and here's the battery bank
with that battery bank I could wild camp for a week with the mains fridge running!