Fuel transfer is mechanically the same whether there are people around or not, and whether you are talking 1 ton of propellant or 100 tons.
Of course it's more challenging.
And it does matter if there's more fuel, you have to have valves and pipes that won't freeze after lengthy contact with cryogenic fuel. And you need larger pressure vessels, which scale in volume differently from surface area. It's not at all the same whether you move one ton or a hundred.