The average amp draw I see for a 12 volt fridge is 7 amps with a 100% duty cycle. Realistically, this averages out to 3A depending on a number of factors.
At 72 amp-hours a day, to keep the fridge from draining the batteries, and using rough guesstimates and no other major loads, two 12 volt solar panels at 216-300 watts each, wired in series and hooked to a PWM (or even better MPPT) charge controller should do the job.
It does cost something to beef up the solar install on the rig, but the return is never having to worry about propane or being level, and if your rig is stored, assuming the panels get reasonable sun, the fridge will always be cold.
