It's not possible to run off gas AND electricity at the same time, is either or, not both.
I have always fitted extractor fans to the top external fridge vent on motorhomes and caravans as I have found them to be seriously beneficial when the ambient temperature is mid 20's or higher.
Strangely enough I have only just picked up my tablet having come into the house after jury rigging a fan onto my PVC as we are planning on having a "day be the seaside" with it tomorrow, so I want a cold fridge in the morning. The ambient temperature here in Weymouth is currently 25⁰ C at 17:45 so tge fridge will struggle without a bit of help.
When I have a bit of time next week I will add another fan and wire both in via an illuminated switch, currently the one is being fed from a permanent 12v supply so no ability to switch it off (other than disconnecting a wire of course)
Over tge years I have also found running the fridge on gas seems to be more efficient, maybe it's because using gas imparts more heat which bizarrely creates more cooling effect? I have always struggled to get my head around how heat in a fridge makes it cool down
