A refer that chases the out-side temperature is improperly vented or has a weak cooling unit.
Seeing as how this fluctuation in food section temperature is a new issue.......sounds more and more like a blockage has occurred in cooling unit between low temp evaporator (freezer) and high temp evaporator (food section).
Provided there is no obstruction of air flow across cooling unit...insulation fallen down etc. But with OEM fan and and another fan blowing doesn't sound like air flow is the problem.
Remove thermistor from clip (on fin in food section) and let it hang down towards bottom of food section. This will force cool fridge and maybe get you thru your trip.
