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Vent the electric compressor fridge to the inside of the camper. There will not be a problem in the warm weather as you will either run the A/C or vent with the windows open and the vent on the roof (maybe with a fan). The added heat from the fridge will be insignificant. Every vent to the outside creates another place for leaks and bug ingress.
All I have ever had in my Scamp has been electric compressor refrigerators and it has never been a problem with the added heat, Of course we generally are hooked up and we have solar power for off grid.

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