As it happens I just went through this. I have a Tuffy deck in my JK that I wanted to retain. I also wanted to get a fridge that I could keep in the back of the Jeep somewhere and not have on the seats. I looked at the dimensions of models from ARB, Dometic, and others. All are too tall to fit under the Tuffy deck. I ended up with an ARB 37, which fits perfectly on top of the deck. It is tall and a bit inconvenient to get in and out of, but it’s certainly usable. One reason I went with the ARB over the Dometic is that the ARB lid opens in two ways. You can hinge it up, which is rather tight when a hard top or soft top is on, or you can detach the entire lid with a kind of sideways tearing motion. With the lid off, it’s much easier to reach in. It didn’t seam like the Dometic lid can open in that way.
BTW, the ARB 50 has the same footprint as the 37, but is about 4-5 inches taller. That extra height would make it unusable on the Tuffy deck unless the Jeep was topless.
It is for this reason that I own both a 37 and a 50. I got the 37 to use in Moby with his deck. Of course, now that I no longer need rear seats for people, I just carry the fridge where the driver side rear seat used to be.