I have had to deal with this same problem some years ago. I contacted a chemical outfit that specialized in clean up stuff for car dealers particularly used cars. There is a spray, usually purchased by the gallon called Arabesque. It leaves a fairly pleasant odor as time goes by. When it is initially applied it is a pretty strong & raunchy smell starting out. Everyday or as frequently as you can go in to the RV and spray the fridge, and in the adjoining areas where this may have permeated and on the way out the door Just give the whole thing a couple of sprits. Close it up and let the sun warm it up. Do this daily for a week or so. There may be a car dealer that would sell you a spray bottle full of this stuff rather than having to buy a gallon of it.