Can't be much less than 1800 per wing. What with 2 G/A and a divert to think of for reserve fuel. Our co min fuel is 3 tonnes which is only a few kgs less. Land with less than this and an ASR has to be filed.
I think you will find that when flying it will be less due to the cold soak of a flight reducing the fuel temp so allowing more efficient cooling. Remember the MM figure has to allow for a vast range of ground temperatures (tropics to the poles). Only a guess though.