In hot conditions opening and closing you fridge all the time for drinks, I think you'd be pushing 3 days.
Thats why even going to the Murray I take my Baileys Ice Box, best ice box ever imo,
When every one else has run out of ice my Ice box has plenty, plus there is a caravan park about 10 k away.
I take LED flood lights on adjustable poles and move them about if needed like down the bank of the river
with a dedicated 18 ah deep cycle battery in a plastic box, they use very little power, thats for sure