I was having batteries v fridge problems (coupled with ignorance) & tried various methods of moving icepacks from freezer to fridge, turning the fridge down/off at night etc then i read this (from the power saving tips thread)
"Fill the ice box of the fridge with ice packs, turn the thermostat up full and only power it up when on shorepower or the engine/genny is running. They seem to stay cool for about 48 hours without using any battery power. Note: You must turn the thermostat up full.
Keep the fridge as full as possible and open the door as little as possible. "
It works so well that i still haven't had to work out whether it's my batteries (only 2 & of uncertain health) or the fridge (very old, sounds like an unwell dolphin sometimes) that needs replacing.
It's easy to get into the habit of switching it off & on at the fuse switch handily placed near the ignition key
Now it's winter lockdown noncruise time the fridge is off permanently therefore extra storage space.
you put the beer, hard cheese & stuff like that at the top where it gets coldest (it never has frozen yet for me) & your salad type stuff at the bottom
yes, ice packs in the freezer, no need to move them to the fridge when switched off either.
I also put bottles of water in cos the fuller the fridge is the better it works