I agree with TIDALWAVE. Pre-cool a couple days, place prefrozen cubes in your freezer, and circulate the cold air with an interior battery powered fan. Good advice. Several years ago, I had a trailer with a Dometic fridge that I installed a non-thermostat controlled fan under the outside fridge vent. That helped some, too. Dometic fridges in RPods have a thermostatically controlled fan under the outside fridge cover, but they don't cycle to on until the outside temperature gets pretty hot. They're more of a temp holding device rather than really helping to cool.
RV fridges are notorious for their cooling inefficiency. The three Dometics I've had were all pretty poor. The one Norcold I owned was a little better.