A person over on the JeepGarage
forum (post #4603) has done exactly that. Used the smallest version of the Titan drawers, which seem to fit perfectly, and used an actuator to raise and lower the drawers. Looks like he has built a frame and a floor as well to accomodate.
The biggest problem that I found, as I was looking at doing the same thing, but was persuaded by others not to, was the extra weight of the drawers. They weigh 70kg alone, and then you still have to add a frame for the hinge to attach to, the actuator (or struts), and a floor... your looking at almost 80-90kg of dead weight before loading anything.
Other things to be mindful of is the height of the roof and the size of your fridge. If you have a big fridge on top of the drawers you might find you don't have the height. If you do have the room for it then you'll probably loose half your vision out the back. Not a deal breaker but something to be mindful of.
I've gone the same concept but I'm building my own drawers out of aluminium to save on weight. I'm having the fridge mounted to the floor and either one or two drawers stacked next to it. I've built a frame for the floor and it's hinged with the same actuator the other guy used to lift it. I have the Waeco CDF 35 and with it attached directly to the floor and as close to the tailgate as possible, it's possible to open it up from the tailgate window rather than opening up the whole tailgate. The floor still hinges up high enough to get the tyre out without removing the fridge. The height of the fridge is lower than the stock cargo cover too, so can be hidden from prying eyes.
Hope the information helps