Exactly why I went hog weasel on the size. Man that 12kW was heavy as hell for us.Once the oven is up to temperature, it will cycle on and off to regulate. Same with the top plates.
So yes if you turned everything on (bake not broil) at the same time you would be pulling 11,100w or 46.25 amps but as the oven got up to temp and your gravy is simmering etc, that draw will go down.
BUT, you have to rate the inverter and battery for that crazy moment when "her indoors" cranks everything on.
Now if she is running the clothes dryer too and its getting warm in the house.....