That 6 amps is wrong, did you look at the back of the fridge and get the numbers of the plate on the compressor
My 7.5 cu ft apartment fridge draws approx 1amp at 120vac, that's 10+ amps into the inverter
But the start up surge aka lock rotor amps of the compressor is 10+ amps 120v, that's 100 amps start surge off battery power into into the inverter
6 amps might be the start surge, which would be very low ( I like that )
Running load will be less
Put the inverter close to the batteries, and run an extension cord to the fridge for the low amp 120v