On our previous RV, we also wedged our Haier residential replacement with Styrofoam and spray foam insulation to keep it in the compartment and insulate it. We did experience a draft in cold weather coming through the outside vent. At the top there were metal angle pieces that we attached 2-sided sticky tape to the top of the front of the fridge frame and that holds very well. It was almost a perfect fit for our original Norcold, so very little work had to be done to the trim.
We used bungee cords to keep the doors closed when we traveled.