We travel with our fridge off and have the same experience as gbaglo. We also use a couple of those blue plastic frozen rectangle/cube things (?) to help the situation.
I think that keeping the freezer full with frozen food and those blue cubes is the key. Then when the fridge is off, all that frozen mass can keep it cold for quite a while.
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Eric (and Mary who is in no way responsible for anything stupid I post)
"Beware of false knowledge; it is more dangerous than ignorance." George Bernard Shaw