I have seen this done in 2 caravans,both times a larger capacity fridge was able to be fitted.

They also closed off the outside venting to stop dust getting in and fitted a fan at the back of the fridge and vent on top of the fridge.The air draws in under the fridge and out the top,it also has vents in the side cupboards.

The 12/240 type fridge is a lot lighter than an old three way too.

Jim