x2.
As you know we have a big dual zone fridge/freezer. There is only 2 of us and we fill the fridge everytime we go camping and we're glad we didn't get a smaller one. It is big and heavy. To be clear, the fridge section in mine is around 47L IIRC. We fit meat, veggies, fruit, milk and drinks for at least a weekend. Probably more like 3-4 days. We fit everything. The freezer is for ice cream of course. (And bait).
So I dare say a 45L will suffice. We could certainly use the space better. Leave out some veggies that don't really need to be cold, smaller milk, less beers, etc. It depends how luxury you want to be really. Bigger than 45L makes the food side of camping easier, but it makes packing space a nightmare!

