Plus, plugging straight into the 12V socket might be asking for trouble – overloading, fire hazards, not fun.
There's no concern for overloading or fire from using the 12v socket with a fridge, this is how they ship and are intended to be used. Strapping them down is important of course. With that being said, I'm not certain that a fridge of any notable size would be able to fit
over the rear seat headrests in the event of a crash.
For the rest of the thread, I'll admit, I haven't read through all 9 pages, but I have had (in order): ARB Classic 50Qt, ARB Essentials 63Qt, ARB Zero 63 Qt, ARB Zero 47Qt, and a Dometic CFX3-75DZ. I also had one or two cheap Amazon fridges, not even worth mentioning.
Overall my favorite goes to the Dometic 75DZ, simply because frozen meals and ice cream. However, it is huge, and overkill. We use it in our Sprinter and can go weeks with only minimal restocks. Of course, the frozen meals are super easy given that the Sprinter has a microwave and induction cooktop, neither of which I am planning on carrying in the Grenadier.
Least favorite, the ARB Zeros, both had horrible condensation issues no matter the set temperature. Normally I set them to 37ºF (3ºC), but tried up to 42ºF (5.5ºC) and down to 34ºF (1ºC) with the same condensation all over the interior side walls. Additionally, they seemed like they needed to run much more frequently to maintain the desired temperature. With that being said, the 47Qt lived in my better half's Tacoma for over 2 years off of the single starting battery (upgraded to a Group 27F AGM from a Group 24F) and a 80W hood solar panel. It did shut down several times due to "high ambient temperature" though. The 63Qt Zero was in our Tundra after we got the AT Overland Atlas topper and never had an over temp error.
Notable mention goes to the ARB Elements fridge, as it was designed for exterior use (and was installed on a fridge slide in the bed of my Tundra). Happily kept our food/drinks at 37ºF (3ºC) with ambient temperatures above 120ºF (49ºC) in Death Valley.
What will the Grenadier get? I'm leaning towards a Dometic CFX3-45 as the happy medium in sizing (I think the 55IM would be overkill) on a tilting fridge slide