Rent a ozone generator.. Place in fridge close door best you can in a few hrs.. You should be all set...if you rent a room size unit.. You can do the entire RV in a day or two..You just can't be in the Rv when the ozone generator is running..
Coffee grounds. Take a plate or whatever will fit in frig, and spread out coffee grounds. Run frig. overnight. Used to work for a trucking company and that is what we did after hauling onions. Coffee would absorb the smell.