Something to ponder for 3-Way Fridge users .....
There is a trend I believe on Campsite to meter electricity? If you ran your 3-way Fridge on Metered Electric on when on site, and also have it running on Electric when at home so it is ready to use when you go away, then you would actually spend significantly more on electricity in a single year than a 240V AC Compressor Fridge/Freezer costs to
buy AND run for that year.
You could actually afford to replace the Fridge/Freezer every year for a brand new one and still save money!
What this also means is that IF a compressor Fridge Freezer breaks down when on holiday, even just throwing it away and buying a new one from the local "Currys" equivalent will be cheaper than running a 3-way.
I've never had to replace a Compressor Fridge in a Camper or Motorhome though, so that is a bit academic

(I did buy a spare Compressor Fridge for the Camper in case it broke - but it never did. That was £80 wasted I suppose. I wonder how much a call-out would be to fix a burner issue on a 3-way?)