I don't use my grill that often. But that's me..
As to the fridge, more facts are needed. You must do the math. How many amp does the fridge use? How many amp hours are you 2 batteries? Now add in what you will use in one day. Without that info, your question can not be answered.
Just an FYI: Is not the amount of batteries you have on board. Its the size of the bank, meaning amp hours. Also the type of battery. So lets say you fridge pulls 10amp. Which is a lot but keeping numbers round! So it each battery is rated 100Ah X two = a bank of 200 amp hours. Flooded batteries can only be drained down to 50% before damaging, AGMs 40% and Life04 to 20%. With flooded, thats 10hr of use that will bring the bank down to 50%. Now this is not accounting, for other loads. With AGMs, thats about 11 hours.