Here is Hurricane MK1 data. Max take of weight is 6793 lbs (3081 kg). So everything above these in CLOD is just wrong.
I checked difference between SPit MK1 (without pilot armour plate) and MK II (with pilot armour plate):
P.7280 ( MK II) - 6172 lb. (2800 kg)
N.3171 ( MK I) - 6050 lb. (2744kg)
..This aeroplane ( MK II) was fitted with a bullet-proof windscreen, armour plating over the petrol tank and externally, apart from the radiator, was similar to the Rotol Spitfire I, N.3171, previously tested at this establishment. The radiator of P.7280 is of the Morris type and tests were called for to determine the suitability of this radiator under tropical conditions. Internally, one difference between this aeroplane and N.3171 has been the fitting of armour plating behind the pilot in the Spitfire II. Generally, any change in performance or handling can be attributed to the change in engine and radiator alone. "
So Spitfire MK1 with aditional pilot armour should have take off weight ab. 6123 lbs ( + 73 lbs armour) - 2777kg