It can be done rather clean. The 4" size makes it easy.
4" hole saw
4" flexible duct
4" grill to make it look nice on the outside.
Depending on your layout its possible you could drill a 4" hole inside your lower kitchen cabinet that is next to the fridge. Then just crack open the cabinet door to let cold air into that space.
When running on propane i would cover the 4" hole with something. 4" pipe plug might fit perfect. Even duct tape would work as you would not see the hole inside the cabinet.
Use a fan to blow the air from the cold cabinet into the warm fridge ventilation area. Im currently feeding 79F cold air into my fridge vent space. Outside air must be in the high 90s. Fridge air temp hasnt gone over 39. The technique works good if youre using the trailer AC anyway. Danger is propane leaking back into the trailer. (although it would most likely fall down and out of the side vent of your fridge, since the 4" hole you drill will probably be higher than the lower vent) Adding a secondary propane detector wouldnt be the worse idea for added safety. Or dont try the technique at all. Only sharing because it has worked good for me and i understand the danger. I have my propane turned completely off on days like this. Not gonna be cooking inside on the stove.
