Turning on the fan that removes the heat from burner in the outside compartment will help improve refrigerator cooling efficiency (if it isn't already on). Also, adding a little battery operated fan inside the refrigerator will help circulate the air and cool things down, too.
Link to previous post on refrigerator fans:
In mid-summer, when temperatures are over 110 degrees here, besides traveling with the refrigerator ON, we freeze water bottles and put them in the door and around food (especially meat) while underway. Then, when the ice thaws, we drink the water and replace the bottles with more frozen ones.