Thanks for the update! I'm glad the campground was able and willing to accommodate you so well.
As a rough rule of thumb, absent any better information, the fridge probably consumes somewhere around 1 pound of propane per day. Propane-wise, you could expect at least a month with two 20-lb cylinders (filled to their actual safe rated capacity of 20 pounds, maybe a little less if you use cylinder exchanges which at least around here are usually only filled to 15 pounds).
The limiting factor in most cases is battery power if you don't have a solar setup and are not plugged into shore power. Of course, if plugged into shore power, presumably you aren't using propane for the fridge anyway.